By "this simple feeling," do you mean love?

Homoeroticism, yay!

Those moments of plot, dialogue, acting, etc., that fans delight in interpreting as homoerotic.

It probably originates from the old days, when the homosexuality taboo was serious enough that every gay pairing was considered a Crack Pairing, so when authors wrote characters as very intimate with each other, everyone just accepted that they are just very good friends, and moved on, or when they wrote outright references to homosexuality, everyone just laughed at the sheer absurdity of the thought, and moved on.

With the emergence of Yaoi Fans and Yuri Fans, and the more open-minded writers, this changed forever. Nowadays, fans willingly interpret any interaction as potentially gay, even for characters without canon orientations and even for those specifically stated by their creators to be straight.

In the related trope called Foe Yay, even rivals or mortal enemies can get this treatment by fans and writers alike, especially if they have a more friendly past together, or one is inordinately obsessed with the other. In Fanfic, this is the direct cause of many a Slash Fic.

This trope does not include genuine ship teases or scenes of intentional Homoerotic Subtext between straight characters.