I feel gross touching my partner..

i feel so so guilty about this and i don’t know what’s wrong with me but my partner (we are both 19) always fucks me and i love it but when i try to return the favor to her i really don’t like doing it. it grosses me out and makes me uncomfortable for some reason. i still do it and offer because i love her and i know she wants me to do it. sometimes it’s better if shes fucking me at the same time i am and i also don’t understand that. she’s really masculine and i’m super feminine so maybe it makes me feel less feminine doing stuff to her? i really don’t know and i tried bringing it up to her but it just made her feel shitty and she was pissed off at me for it which i don’t at all blame her. sometimes if i imagine doing stuff for a guy i feel gross about that too. could i be asexual even though i like the idea of things being done to me?? sorry for the long post.