Is it wrong if I cheat?

I've been going out with my girlfriend for 8 months and we don't have muh sex rarely even once a month. I have told he that I would like to have it more, but I am going on a lads holiday soon and when we go away we will have had it once in 13 weeks. If i'm drunk I may be inclined to cheat, is that a bad thing? I have told her I want more sex an many occasions