I can't stop thinking of another man!

I'm not sure what to do lately me and my man have nothing but problems. He does something nice like take me out to dinner and I hate going cuz he always throws what he does for me in my face. Always belittling me and calling me names and I hate it and even tho that shouldn't justify how I've bee feeling but there's a guy that I can't get out my head I haven't talked to him but I see him always looking at me at the gym and he said I'm really beautiful. But I'm on the verge of wanting to talk to him and this guy is 21 and I'm 9 years older then him so I know I could never have a relationship with him I just want that happiness back :(