S8 but have gay fantasies

I'm a s8 lad,in a happy relationship with my girlfriend but for years I've had the urge to hook up with a lad,I don't fancy men though,but the sex intrigues me,I've played with myself before and used toys and really really enjoyed it. I've been tempted to meet up with lads but I've been too scared and didn't want to cheat on my lass. I don't think she would understand even if I told her and she thinks it's a bit wrong anyways. I just don't know what to do,I even think there's something wrong with me for having these thoughts as well