Cop Boyfriend

Female Amateur Sleuth types of a literary nature need to have some way to get involved in cases. Or they need some kind of "insider" to help them with their cases. Enter the Cop Boyfriend, who's practically a requirement in fiction. He's either a cop, in the FBI, or is in some other law enforcement agency. As a general rule, he does NOT approve of his girlfriend messing around in cases where she shouldn't be. Of course, most police don't appreciate people nosing about in police business, for reasons of safety at the very least.

A non-romantic attachment is a Friend On the Force.

Anime & Manga

 * In Death Note, Raye Penber, an FBI agent sent to Japan, does not want his fiance, Naomi Misora, to get involved in the Kira case.
 * Unfortunately for him, she was the better detective between the two. If he had let her get involved, the series would be one and a half volumes long, and both of them would.

Film

 * In Harley Davidson and The Marlboro Man, HD robs banks indirectly, by robbing bank robbers (which he then keeps the money). His girlfriend is an LAPD patrol officer who has no knowledge of his, ahem, extracurricular activities.
 * Ram is in a relationship with a corrections officer named Ganga in the Bollywood movie Khalnayak. She goes undercover to help catch a notorious criminal that escaped from Ram and caused him to lose his reputation as a detective...and gets in way over her head when said criminal goes all Yandere over her.

Literature

 * In the Claire Malloy book series, Claire's boyfriend (later husband) Peter Rosen is a Cop Boyfriend who does not approve of her getting into trouble.
 * In the CeCe Caruso book series, CeCe's Cop Boyfriend, Peter Gambino.
 * Psychic Eye Abby Cooper's Cop Boyfriend Dutch Rivers later ends up working for the FBI. Dutch is somewhat subverted in that he starts out as a disapproving boyfriend (plus his girlfriend is a psychic), but later grows comfortable having her help him on cases.
 * Stephanie Plum has both an off/on Cop Boyfriend (Joe Morelli) and an off/on bounty hunter/mercenary boyfriend, Ranger. Ranger is somewhat more cool with Stephanie's cases than Joe is.
 * Kinsey Millhone rarely dates, but she has had a Cop Boyfriend (Cheney Phillips). Kinsey is an ex-cop and PI, so the disapproval thing was not an issue.
 * Tressa "Calamity Jayne" Turner has both a state trooper and a ranger as love interests.
 * In Tanya Huff's Blood Books (and the TV show made from them, Blood Ties), the heroine is a cop-turned-PI, and her human love interest/former police partner fills this role.
 * In A Mantra For Murder series, A.J.'s cop boyfriend Jake.
 * Invisible Monsters's protaganist has a cop boyfriend who uses his knowledge from working in vice to help her and Brandy steal and sell drugs... among other things.
 * In Earlene Fowler's quilt-themed mysteries, quilter and Amateur Sleuth Benni Harper dates Officer Gabe.
 * In the novels by Ngaio Marsh, artist Agatha Troy has her husband, Detective Chief Inspector (later Chief Superintenddent) Roderick Alleyn. Several of the novels begin with events that happen to her (painting a portrait at some country house, or going on a trip by herself), and he comes into the picture later. He's never happy about his wife being involved in crime, particularly murder.
 * Daisy Dalrymple from the Carola Dunn novels of the same name eventually marries the Inspector Lestrade of her series. Since it's set in the 1920s, he's remarkably enlightened about her solving what seems to be most of his cases.

Live Action TV

 * Kate from Angel is a pretty good (and rare) female example, though she and Angel aren't actually romantically involved. She has the disapproval down pat, which intensifies to the point of antagonism after.
 * Lampshaded after Kate leaves the show. A stumped Angel hires a private detective who has a friend on the force. The cast complains they are supposed to be private detectives with a friend on the force.
 * The Closer - Brenda's boyfriend-then-husband Fritz is an FBI agent. Brenda belongs to the LAPD, but she has often found it useful to have an inside source in the FBI who can get information or do things that the LAPD cannot. He will sometimes offer to help, but there have been times when the FBI and the LAPD both had mutually exclusive interests in the same suspect (for example, a suspected murderer may be a mid-level member of a crime syndicate, and the FBI may consider his usefulness as a snitch above the interests of the LAPD). In these cases, Brenda will do something underhanded, in essence tricking the FBI, and, more personally, Fritz. Fritz will often take this very hard, and will call Brenda out, often gaining the sympathies of the audience (Brenda will often take an "ends justify the means" defense with Fritz when he reacts this way).
 * Crossing Jordan - Jordan, a medical examiner, shouldn't be anywhere where a freshly-found dead body isn't. But she constantly goes snooping, often dragging Det. Woody along with her (and just as often following him to where the action is).
 * In The Sarah Connor Chronicles, Sarah's landlady Kacy Cotton had one, whom she says left her after she became pregnant..
 * Dale Arden's boyfriend Joe in the recent Flash Gordon series is a cop, although this is more about him trying to break the Masquerade.
 * Detective Reese from Birds of Prey fits this role to a tee, initially disapproving of Huntress' vigilante activities (he tries to arrest her at their first meeting) but eventually becoming a valuable resource.
 * Veronica Mars has a private detective/ex-sheriff father. She doesn't always need him to get cases, but she did learn most of her sleuthing skills from him.
 * Through part of season 1, she actually did date a cop, who made regular appearances even after they broke up.
 * In Stargate SG-1, Sam had a cop boyfriend for awhile whose crime-solving expertise was used in a couple episodes. But for the most part, this trope is averted, because Sam's the one in the top-secret military operation, and the cop boyfriend is mostly not allowed to get involved with her work at all.
 * Eventually, an earth-bound mission irks his suspicions too much and he ends up getting a glimpse of the larger picture (and shot with a laser beam). Rather than end the relationship by just cutting him off, Sam is forced to get him clearance and fill him in on the basics of the Star Gate program.
 * In The Sarah Silverman Program Laura starts dating the police officer Jay in the beginning of season one. It looks like they'll be getting married soon.
 * In Moonlight, Beth's boyfriend is a district attorney. He is very adamant about her staying away from cases he is investigating/prosecuting, although he has no idea that she is slowly falling for Friendly Neighborhood Vampire Mick.
 * In Tracker, Mel's on-and-off boyfriend is a police detective. He is constantly doing favors for her, hoping to rekindle their relationship. He even searches for her missing fiancé, who disappeared years ago. He is distrustful of Cole, whose quirky personality and speech patterns don't help matters.
 * In the first season of Charmed, there's Andy for Prue.
 * Dyson for Bo in Lost Girl.
 * Sally MacMillan has her husband, San Francisco Police Commissioner Stewart Mac Millan. Since they are a married couple, they regularly discuss crime and its solution (frequently in bed or some other intimate setting).
 * Detective Beckett will be Castle's Cop Girlfriend if they ever resolve their Unresolved Sexual Tension.
 * Booth is pretty much this for Bones, especially now that they have finally.
 * In Psych, Jules is Shawn's Cop Girlfriend.
 * Gender-reversed in The Finder where Deputy US Marshal Isabel Zambada is Walter's Cop Girlfriend.
 * Technically, Juliette from Grimm has one, but since he's the main character and not her, it probably doesn't count.

Visual Novel

 * Angel Starr has at least four or five in Ace Attorney, all of them in different parts of the police department. She uses them to get her information and access to secured areas.