I need help.

Seeing a guy for 13 months now, dating for 5 or 6.

Our relationship feels like friends with benefits though, and I feel like he says I love you back just to not hurt my feelings. I asked him if he is in love with me and he said, "well I love you but I don't know if I would marry you." We don't make plans for the future, I'm not really involved in his life/family/ friends. I feel like I'm convenient for him, I do a lot for him because I like making him happy and we always had amazing chemistry and amazing sex (up until recently) where I feel like he just isn't that into me anymore.

I know this sounds irrational but another thing is that whenever I send a heart, he sends me a blue heart back.. it's just a lot of little things that makes me feel like he isn't sure of me.. maybe stringing me along.

I just don't know what to do.. my friend says there is a lot of red flags and I need to end things.

*edit*

I never questioned he was into me at first, in fact I had never been with anyone who was as into me as I was into them until meeting this guy. We seemed obsessed with each other, completely infatuated. After we began a relationship though, things changed. I did become very insecure, doubting he was actually attracted to me, thought I was enough. I was married for 11 years in a very toxic and abusive relationship so I have issues... But he treats me well and I do feel loved but there is just something off that nags at me constantly, I just can't shake this feeling that he isn't genuine with me.