How do I 22F put more into my relationship with BF 23M

I(22F) and boyfriend(23M) has been in relationship for 6 months. I feel like he barely cares about me. At first he was putting so much efforts but nowadays we dont even talk. And it feels like the relationship has become one sided. He doesn’t call for days. In fact as I’m writing this he hasn’t called for over a week. He tells me he is very busy. While I understand and believe he is busy, I feel like it’s no excuse to not even take 5 minutes a day to talk to me. I reach out. I call, no answers. I text, dry response and then mia. Whenever I try to discuss this with him, he sweettalks me about how he’d never even reply if he wasn’t interested and he’s doing even this much because he likes me. Please offer advice on how should I proceed further with this so called relationship. Another thing stopping me from breaking up with him is because he’s the first one to show genuine interest in me and wanted to date me. I’ve always had low self esteem and think I’m ugly. I believe it to be true because I’ve heard it before. People have said it to my face. Even when I got into this relationship my friends laughed and said how did you get into a relationship. So I feel like I kinda deserve this treatment or I shouldn’t hastily breakup and put more efforts so that he’d genuinely participate in this relationship. How do I put more efforts?

TL;DR – Boyfriend doesn’t put the same efforts anymore so need advice on what to do about it