Being married puts you at a disadvantage for making friends pretty in general. It has nothing to do with med school. If you're married or in a serious long term relationship equivalent, it will be difficult to leave your spouse alone to go hang out with your new "friends." You also are pretty much restricted to only making friends of your own sex for obvious reasons. So what generally ends up happening is that couples make friends with other couples. Forming close, real friendships with single individuals while you are married is not common. And what happens in med school is that the "friends" you make are people you talk to while in school and occasionally meet up with in very large group settings that you bring your spouse to. And almost invariably lose regular contact with after graduation.
So to answer your question, no, there is nothing particularly different about making friends while married in med school vs. in any other environment while married. If anything, you will be exposed to more people. Try making friends when you're married and in residency. LOL, sorry spouse, I know I've only seen you 5 hours this week, but I met this really cool dude and we're gonna go fishing and drink beers on my day off.
Plenty has been written about the difficulties of friendship after college and into your 30s and 40s. Do a google search.