I come more quickly to orgasm when I masturbate

This is normal.  Women who know their own bodies well enough can reach orgasm in under three minutes!  During sex, it can often take much longer.

Your partner can never know (unless you tell him) whether he’s using the right amount of pressure, the right movements, the right speed, if it needs to be constant, or gradually get quicker…  You yourself will know exactly how you need to be stimulated to achieve the right effect.

If you explain to your partner exactly how you need to be touched he will be able to satisfy you more easily.  It may take him a little while to adapt and to get the new technique right.