In humans, we have already selected and mated before the orgasm takes place; not the other way around. Humans select potential mates on a variety of contingent factors. For men, the best possible mate is fertile and is determined to healthy enough be able to raise any offspring to sexual maturity. For women, fertility matters, but just as important is the ability of the man to provide resources so any offspring will have a good chance of survival to sexual maturity.
To be blunt, while there are good and well known evolutionary reasons for the male orgasm, while the female orgasm is a mystery. In short, no one really understands how the female climax is an evolutionary adaption, although theories abound. Some theorists think it is designed to keep a woman lying down after sex, aiding in retaining semen and increasing her prospects of conception. Others suggested that the female climax evolved to make a stronger tie between the bonded couple, by stimulating in women feelings of closeness and trust toward their male partners. Still other biologists reason that an orgasm communicates a feeling of deep sexual satisfaction and fidelity from the women to the man.
In humans, the forming of a pair bond between couples depends on a number factors, such as mutual attraction, timing and opportunities. All of us meet and discard potential mates hundreds of times in our lives and yet on average we are pretty picky, with men having just under seven (6.8) sexual partners in their lives, while women have just under four (3.8).
Ultimately the goal of any pair bond is to reproduce and raise the offspring to sexual maturity as to pass on their genes to the next generation. The methods humans have adapted to achieve this is the relatively monogamous pair bond using sexual intercourse as the means to exchange the required germ cells to that the offspring is has half the male partners genes and half the female partners genes.
Orgasms are the end result of sexual intercourse, which generally takes place after some kind courtship. It is during this courtship that the potential partners evaluate and determine if the partner is a worthy mate. This courtship ends in sexual intercourse which results in, potentially, orgasms for both partners.
It is simply impossible that orgasms could prevent humans from selecting then best potential mates, since they have already selected before intercourse and the orgasm takes place.
Sources:
F. B Furlow & R. Thornhill,. - The Orgasm Wars. Adaptive function of the female orgasm. Psychology Today, Jan-Feb v29, 1996
http://www.cdc.gov/nchs/nsfg/abc_list_n.htm
