Popularity

Just thinking about what makes someone popular?
What contributes to feeling part of the group?
What kind of characteristics does a person need to be invited to a social gathering?
What makes someone exclude you when you know others who were invited to an event?

I just found out that there are two separate parties going on within a wide group of friends, not super close, but definitely on chatting level and pretty much peers in a group.  We were not invited.  It's hard not to wonder what contributed?  My husband's position?  My husband is a particularly good conversationalist.  I can hold my own.  I don't know.  I'm kind of struggling on this one and feeling left out.  Maybe it's because we don't reciprocate enough.  But, I always send thank you's and I always try to contribute to a party somehow.  Maybe it's age.  We're on the upper end of the one group, but about the same age as the other one.