During the process itself, listen to her breathing and the rhythm of her heart. If you notice that they become heavier and change their pace, then she does not pretend - the orgasm is real. At the peak of pleasure, the heart beats very quickly, this is a clear sign that they are honest in bed in front of you.
Dilated pupils are another one hundred percent indicator that a woman is reaching the peak of pleasure. Yes, it is difficult to see this in the dark, plus many close their eyes in pleasure, but if you managed to notice that your lady's pupils dilated in the midst of the process, then you can calm down - this partner is not pretending.
You may have noticed that during arousal, girls' lips swell and redden without any lipstick. If you kiss your partner during the act, then you can feel that her lips are swollen and become hotter. Consider this a clear sign that your partner is extremely aroused.
During sex, the body tenses, as those muscles that are not so active in everyday life begin to work in excess of the usual rate, which in turn leads to an increase in the body's sweating. If both of you are satisfied with the process, then in the end you will both be in a hot sweat.
Muscle spasms are the most accurate indicator, since no girl can imitate this. The fact is that during orgasm, certain contractions of the uterus occur, which the partner cannot but feel. If you have not noticed such contractions, then it is likely that your partner is cheating on you.