What are signs of men cheating and how do I know??? women and men help?

okay i have been wit this guy for four years now and he has been acting strange for like the past 4 or 5 months. the the things he dont do anymore he doesnt say i love you until i say it first (which i have stopped doing) he doesnt take me out anywhere we use to go to the show alot now he says hes uncomfortable sittin in the chairs. he doesnt take me out to dinner he complains about the prices. he doesnt give mages anymore. stop tellin me i am y or pretty the way he initiate is by sayin come suck my ****. no unless i ask for it. he never wants to come home and when he is home we argue. he is a bouncer at a bar so he is gone every weekend and there are A LOT of female numbers in his phone but they are just "friends" when i ask. i just got a new cell number so he just puts me in his contacts under michelle it normally would be "wifey" or MY GURL. now its just like im one of those others females. what should i do???????