There are no strangers here; Only friends you haven't yet met.
William Butler Yeats (one of our favorites), who's also responsible for this gem:
Thinks where a man's glory/ Most begins and ends / And say my glory was / That I had such friends
Once you're comfortable somewhere, it can become easy to shut yourself off to new friendships unless you're desperate (a recent friendship of ours started with: "We should hang out since all my friends are gone but you're still here"), but all we can say is: don't let it. New friendships might be awkward, and you will have some misses along with the hits, and you may have to tell someone directly: "I decided we were going to be friends." (This works surprisingly well.) Still, there's nothing like a new friend to shake things up a bit in your life.
And of all times, the lead up to a wedding is a wonderful time to make new friends -- after all, if these strangers were smart or lucky enough to become friends with your friend, they must have something going for them. (On that note, our guy friends have been pushing for a dating app for weddings. After consideration, our response was: "Maybe not a totally terrible idea?" Let us know if you have thoughts!)
(P. S. Our dorky tip for staying in touch with friends old and new? Regular calendar reminders to reach out to people.)