i actually really don't like the idea of posting pictures with your partner in your profile pic, whatever the site is. it broadcasts a lack of individuality. and, i'll never see the upside to that, no matter how you try and explain it. your profile is yours, it's never your partner's. and, no, you can't share it.
it's kind of like going to the bathroom with the door open. you're going to do it. and, everybody knows you're going to do it. but, it's never ok.