You are not homophobic just from feeling weird if you see two men kissing next to you if you like woman. I mean, I don't like to see people doing it at all in front of others (french kissing, not a small kiss on the lips) and as less I am attracted to the persons doing it, as worse I find it (if I see an "ugly" straight couple kissing I find it also worse as a good looking one)
When two men kiss each other and you like woman, then that discomfort may be the biggest simply because of that, you are the least attracted to that combination.
But as long as you don't try to tell them that they aren't allowed to do it but straight couples are, I think it should be fine.
€dit: Ok , to feel as bad as looking at beastiality pictures might be a strong form of feeling "bad" looking at pictures of gay couples but still, as long as you don't start to talk bad about gay people and as long as you are as nice to them as to everyone else I think you are fine.
