Is it a sign that your wife is cheating if she leaves you all the time because she says you dont show her enough attention and goes off with a guy friend a lot when she leaves you and stays the night?

maybe, and maybe not. It could just be her extreme way of actually trying to get you to give her the attention she needs. see how you can change urself to better the situation. Take her out. make her feel special. Buy her a gift for no apparent reason. cook for her. tell her u appreciate her when she does something/anything for u. give her a bedtime massage. etc. discuss with her what she needs, and tell her u will give her what she needs. But also, tell her it is wrong to be staying over with that guy.

U both can work things out, just find things URL both could do to suit each others needs. Marriage is a beautiful thing, but effort makes its beauty a reality.

:)... all the best, and God Bless ur marriage.