Sensation inabilities

Megan

I don't get turned on by nipple stimulation, and it's really hard for partners to make me orgasm despite good communication and efforts.

I've been having sex weekly or monthly for about the past 2 years. I can make myself orgasm and I do get wet, but not from nipples or partners. (I still get turned on by my partner though, just not orgasm)

Any explanation as to why it's so hard to be stimulated?