Just Partners

Elliot Stabler: You offering to be my partner?
Donald Cragen: I'm not your type.

Elliot Stabler: (grins) I don't know. Maybe I'd have better luck with a guy. Women keep leaving me.

—Law and Order Special Victims Unit

The leads on a crime drama or procedural. This is a male-female relationship, and the duo is usually, but not always, in a law enforcement profession. They do not have to officially be partnered together as long as they don't work with anyone else more closely than they work with each other. They're like the partners of a Buddy Cop Show only, you know, different genders.

The duo typically spends a lot of time together off the job. There's probably a will-they-won't-they element between the two characters. Their relationship must be one of the main focuses of the show, and is usually in the form of a Just Friends scenario. There are often countless instances of She's Not My Girlfriend and Everyone Can See It.

Usually they're an Odd Couple, especially a believer, and a skeptic, but not necessarily, making them fundamentally different in their beliefs. Typically, these characters will also experience a difference of opinion on other faith-based subjects, such as religion.

This trope doesn't tend to pop up on ensemble shows or shows that only have one lead, such as House or 24.

Relationship strength comparable to Heterosexual Life Partners and Platonic Life Partners but with sexual tension.

Examples of Just Partners include:

Live Action TV

Every so often in The X-Files Mulder would flirt with a woman and not notice Scully's jealousy. Outside of that they were all business.
From Castle, there's Castle and Beckett. Castle isn't actually a cop, just a writer who's gotten permission to shadow Beckett.
Dr. Temperance "Bones" Brennan and her partner FBI Agent Booth.
Jane and Lisbon on The Mentalist.
Subverted with Peter and Olivia on Fringe and played straight in certain universes.
Law and Order Special Victims Unit has Elliot Stabler who always works with a woman. Once he was partnered with a man. It didn't go so well.
Danny Reagan and his partner and Jackie Curatela in Blue Bloods.
Myka and Pete from Warehouse 13 are this, heavily inspired by the Scully/Mulder dynamic from The X-Files shown above.
Common to all 3 ((CSI)) series. CSI had Catherine and Grissom until the cast shift, CSI: NY had Mac and Stella. Now Jo is slipping into the part. On CSI: Miami, it's Horatio and Calleigh.