simple.....u get bored, sexually, of what u have. u juss need some fresh pussy that can still get u hard, since uve been with ur significant other for a couple months, and she's simply not doin it for u sexually, its juss becoming boring, she juss cant get u turned on nemore, and ur horny as hell and u need to get that dick licked lol!...and either the sentimental aspect of the relationship is messed up, and therefore u can care less about her feelings, or ur fukked up in the head and have no consideratoins for ppl's feelings......
whateva fukk it.....cheat away!!!!