Thinking during sex

I have a problem I think to much during sex causes me to lose boner alot I want to know how you guys stop thinking when having sex . I love her sex does feel good but I also take so long to cum that it kinda makes me pissed off at myself . I don't want her to feel unwanted or feel likes she doing anything wrong I know she trying her best for me and sucks we she just gives on making me cum I wanna something's that would help me