People fall in love quickly everyday IRL.
You been on The Coli too much breh.
Man after being alone for four years, lizzo could pop up at my hideout and I'm wifing her day one
Lmao, okay I agreed with
@RamsayBolton that the relationship felt too rushed, but this is a good point. Would it have seemed natural if Frank were a beautiful woman instead of a man? Maybe... but my initial reaction was the partnership was purely self-serving from Frank's perspective, and closeted gay Bill was taken advantaged of. That's why I wasn't really moved by the sort of agreed suicide pact they made at the end of the episode. I think I still would have felt that way regardless of Bill's partners' sex.
TLOU story works because we see the full arc of Joel and Ellie's relationship throughout the course of the game. Because of the things that we see happen to them, their actions later on make more sense and are believable.
I don't think episode 3 was great at portraying Bill and Frank's motivations. Sure, I suppose Bill revealed his to some degree in his letter, but, again, I'm more of the school of thought that it's better to show the audience than just to straight up tell them.