I haven't had any trouble developing friendships here, but I really am just developing friendships as I am already in a relationship.

If you're looking to "make friends" as a trojan horse to a relationship, particularly a BDSM one, then you're going to find what "nice guys" have found for thousands of years: that women, especially subs, want a man who is confident and straightforward, and who expresses his intentions clearly. Becoming "friends" with someone you are interested in and then down the road trying to leverage into a relationship is something a lot of women have to deal with, and are probably sick of.

If on the other hand you're actually seriously looking to "make friends" then try the Fun & Games and Question Fetish sections of the forums. They're both great for getting to know people on the site over a period of time, and people are open and friendly there as long as you're not creepy or weird.