They only talk about their partner in a sexual manner - how good in bed they are, size of certain body-parts, how far they're willing to go in the bedroom, and openly compliment/drool over members of the opposite gender in front of others.
The gender of the people above are irrelevant, really.
There's one person on my course that only mentions sexual things about his long-term girlfriend to everyone. We all knew her bra size, how far she goes, how tight she is before he even uttered her name. (We didn't ask for any of the sexual information).
He's told me that the only reason he chose his girlfriend over her sister was because she had a better behind, whilst the sister had better breasts. He constantly drools over images of women, and defends Porn more than anything else.
I want to tell her, but maybe she knows he does it? I dunno.