Interesting topic/theory on the birth control and partners. Possibly some lackadaisical choosing's if one isn't afraid of, or planning a pregnancy?
As I've grown older and have had my children (no desire for more) I do experience a shifting perspective as to what I find attractive in a partner.
As far as choosing a love partner, I've found the relationships ripe for most growth often present themselves to both in a sort of synchronistic fashion rather than a carefully planned set of qualities/attributes, and really even any thinking/planning by either partner.
I do have friends and family who've chosen their partners in the same way they do a career and these are safe and often times work w/o a lot of extreme up's and down's, but seem to lack real passion when it comes to spiritual/soul growth.