We have friends that are getting married after us and have invited us, do we need to invite them too?

They're my fiance's friends, I really don't know them very well at all. I haven't spent any time with them and they don't seem important in his life. He hasn't mentioned inviting them, but it seems like the right thing to do. Our wedding is going to be very limited though, about 60 people with half of those being my family. Not sure if we're obligated to invite them or not.