Is it normal to not be yourself when you're in love?

I don't know if I possibly "lost myself" while being in love with my boyfriend. It's weird. I noticed that he obviously liked me for who I was in the beginning and Im still that person except not when Im with him. I feel like overwhelmed of always trying to impress him, or just being obsessed with him and all for him which has resulted in me losing myself and therefore, he has been losing interest in me little by little as well. He recently mentioned he doesn't have that spark anymore and I asked how long has he felt this way and he said its been a while which doesn't surprise me at all. I always questioned why he would act funny w/ me and I would ask so why is he with me then? But I had faith because he was still with me no matter what so I gave him the benefit of the doubt. But turns out I was on to something. I just remembered how into me he was in the beginning when we were just getting to know each other and not to mention "friends with benefits." We were seeing each other for a really long time before we became official and yeah he was always enthusiastic and willing to give me second chances whenever we would fall off. There were times where he wasn't ready for a relationship when I was and he would call it off but then he always came back to me.

But I feel like this time, he's pretty sure theres no more chances left in him. I understand why he would be a little disappointed in how I "turned out to be" because I also don't like who I am when Im with him, but without him, I feel fine and I'm sure if he saw me with other people he would remember why he started dating me in the first place. Is this normal? to lose yourself when you're in love? To be honest, I feel really lost when I'm with him like I have no personality and he sees that which is why he doesn't like me anymore.