Really nice so far! Have you ever seen the gay movie 'Plan B'? Cos this reminds me a LOT of that movie, which was great (one of my all-time favorites).
Same premise of straight guy finds out that his ex is dating a new guy, and decides to get revenge by cozying up to her new boyfriend so he can break them up, but then the two guys have heaps in common, become close friends, and fall in love with each other (then the new boyfriend finds out about the guy's original plan, etc). Just curious!