I also think it's a personal choice what kind of relationship you want to have (the two of you). At some point you need to discuss things like:

Do both of you *want* to have friends of the opposite sex? Is this a better idea in theory than in practice? Would you prefer your partner didn't have them? Are you willing to suffer feelings of insecurity and jealousy to let him/her keep those friends? What can you do for each other to make it easier? What's your "comfort limit", and what would change it?

I'm sure you've been through a lot of these, but if you can keep it general, not specific, and agree on the main points, you'll have some answers, at least.