Watch a man during sex.

How often does he change positions? If for sex you change 1-2 positions - everything is buzzing. If he constantly twists you and cannot finish in any way, most likely he does not have enough emphasis and friction. Your vagina is too wide for him. Another wake-up call - if during sex a man's erection falls, and it's hard for you to get an orgasm - this can also be due to weakness of the pelvic floor muscles.