do i have to end it?

i love my partner we’ve been together 3 years and we’re 18. they’re my first love and i know i see them in my future, there’s an incredible connection and i don’t want them to slip away. the problem is i’m not sexually attracted to them, i don’t think i’m sexually attracted to anyone. they will touch me and pleasure me but i feel uncomfortable doing it back. they once got mad at me because i told them i might be asexual. they took it personal and said it made them feel shitty about their body. so i took it back and told them i think they’re perfect and beautiful. i try to pleasure them back and sometimes i’m enjoying it but rarely. i don’t know what to do. if i tell them i’m not actually sexually attracted to them they are going to leave me. especially since i’ve lied about it for the sake of their feelings and our relationship for so long. do i have to end it? is it only fair?