There's a scientific reason and it involves you!
Are there days she feels a bit too lose for your liking even after you haven't seen her in a while? One would conclude that your girl has been busy sleeping with other guys right?
There's a scientific reason as to why her vagina would feels different than the other times during sex and it involves you.
Vaginal tenting is the name scientists use to define this phenomena.
It occurs when a woman is aroused to the point that the muscles in her uterus tense and rise therefore creating more space in the vagina.
According to The Center for Sexual Pleasure & Health, the vagina, when unaroused, resembles a collapsed tubes with touching walls, about three or four inches in length. Arousal causes the process of tenting to occur which then helps with vaginal lubrication and the thickening of vagina walls for better and more satisfying sex.
Foreplay is the answer to all your bad sex. While women take longer to get heated up for sex, taking your sweet time to make her wet and ready will make penetration a highly pleasurable sensation for both of you.
Usually it takes ten or more minutes to get a girl going. However, if you're lucky enough... she'll be ready to jump you before you set your gear into drive mode.