How come i always ejaculate when i masturbate but i don't always ejaculate via intercourse?

Friction: You can control the amount of grip strength to get yourself off but it sounds as if you need more help with a partner. A sex therapist can help redirect your efforts to be more in tune with a partner.

Depends: Since you can ejaculate with masturbation, there may be some psychological issues you are having with your partner. An open conversation with her as well as perhaps with a counselor or sex therapist may help. Good luck.