Honestly why would you even want to be with someone you believe doesn't love you? It sounds like you have low self esteem; otherwise, you'd know that you deserve more than that. Truly you do.

When yr only 21, you obviously haven't had much experience& it's easy to be seduced the allure of someone so much older. At this stage in yr life, the age gap DOES matter because there is so much of a difference between you in EXPERIENCE; HE'S HAD SO MUCH EXPERIENCE IN LIFE AND YOU HAVEN'T.

You're honestly better off admitting it wasn't meant to be and letting him go. Only then can you start a better and hopefully, eventually, meet someone yr far more suited to. Remember at 21 yr too young to settle down anyway. Forget him& live yr life. At first it will be hard to forget- but when you immerse yourself with friends& hobbies & start a new life, it won't seem as hard. 'Time heals all wounds.' Good luck.