To find out that your loved one was cheating on you, deceiving, living a lie, is always a frustrating, heartbreaking experience. Some may say cheating is cheating regardless of who that person was cheating with. Theoretically, yes.
However... as a gay man, it would be much worse for me if I caught my boyfriend/partner/husband cheating on me with another man, than with a woman. I do not think I will ever forgive him, if it was with another man, but I will probably be more flexible in listening to his ‘explanations’ or considering forgiveness if it was with another woman. [ Don’t take this as granted, future boyfriends! :-) ]
Likewise, I always thought that for a straight woman it’s much worse if she caught her husband cheating with another woman, than with a man. Well, apparently, it’s not (always) the case, at least according to this article in Aravot daily (AM), reportedly based on one Armenian woman’s real-life experience where she says: “There is nothing worse for a woman to see her husband in another man’s arms” [“Յուրաքանչյուր կնոջ համար սեփական ամուսնուն ուրիշ տղամարդու գրկում տեսնելուց ավելի վատ բան չկա”]