There was some serious research I read a few years back (not fluff in Cosmo...) that looked into whether people that had been ejaculated into had better mood than people that had not (i.e were using barrier contraception).
The findings (from memory) indicated that women taken vaginally, and anyone taken anally had more positive feelings about their partner if questioned some hours later compared to anyone fucked using a condom, or withdrawal.
Oddly, satisfaction with the partner was NOT dependent on having had an orgasm.
As I remember it the research initially intended to show that intercourse to internal ejaculation (regardless of other forms of BC) caused the partners to chemically bond.
I have encountered women who confirm that the feeling of their partner ejaculating into them can make them orgasm themselves - and at least one gay guy I used to work with admitted (although it was unsolicited and caused conversation to die that day in the office) that he loved having his bf come up his ass and then spend the morning feeling it inside. A sure case of TMI....
