How wet you get can be influenced by pregnancybreastfeeding, and even where you are in your cycle. Part of the thrill of sex is experimenting with different positions. So before intercourse, make sure to indulge in lots of foreplay, enough so that your vagina swells with excitement and becomes sufficiently lubricated. Please remember that it is difficult for many women to orgasm throbbing in vagina after sex intercourse.
Some women learn to contract their vagina to try to fake it, but it would be rare for a woman to be able to contract in as quick succession as her vagina would be contracting if it were a real orgasm. Part of the thrill of sex is experimenting with different positions. If she says she is orgasming, but you still suspect that she is faking orgasm, then the only way to know for sure is to try to determine if you feel her vagina contracting.
It's unclear what type of pulsing you are inquiring about. Vaginal contractions are involuntary during orgasm. The discomfort lasts at least a few hours or even into the next day.
What causes vaginal dryness? Relaxation of blood vessels can cause a noticeable, red discoloration of the skin of the neck and chest that may go unnoticed with the lights off.
There is definitely a pulsing of the muscles that surround the opening of the vagina at the time of orgasm. This happens because there is increased blood flow to the area and the muscles of the vaginal wall may have some minor contractions.