Please help !

I have a boyfriend , we been together for 1 year and 5 months . Today I looked at one of my guy friends and started thinking what it will be like to date him and would he do all the bad stuff my boyfriend has done . Idk if I'm loosing feelings or not . How do you know if you are loosing feelings for someone. My mans has done some pretty mean stuff and every time i look back at it I feel some type of way , when we broke up he said he didn't feel the same way . He said he loved me but didn't wanna be with me . And then we got back together like 2 days after . Idk how to feel !