Idk how my boyfriend actually finds me attractive

to start I’m in a loving st4t relationship. I feel like an ogre and I genuinely believe that I’m unfuckable but my boyfriend always tells me that he thinks I’m the prettiest girl he’s ever met and he’s always very horny for me. problem is I genuinely can not stop thinking that he’s lying to me and himself and that he’s just forcing himself to like me because I’m very kind and nice to him and he likes talking to me. I genuinely don’t know what to do because i feel like if i keep acting like this he’s gonna leave me at some point. I need advice.