I’m scared for no reason. Help?!?

Ok so I’m scared to masturbate but my boyfriend can finger me and eat me with no problem. When he does it it feels good and I orgasm a few times. But when it gets to a point where I’m horny and alone I can’t bring myself to put my own fingers inside. I can’t even bring myself to touch myself unless I’m washing myself. I don’t know what it is, I just can’t bring myself to touch myself. But somehow I have no problem with my boyfriend doing it. Please help? Any tips?