It is very common. Don't let it bother you. Forget them! And make new friends. Friends are supposed to be with you through thick and thin and if they can't be by you, you are better off without them.
They could be feeling torn between you and your ex as well....so make it easy on them, reduce the awkwardness by just walking away.
Some women feel threatened by their newly single friends....they watch over their husbands like hawks and because you are now single, their husband who was hitherto safe with you when you were married is no longer safe with you, so they distance themselves from you and their husband will be well-advised by them to do as they are told or there will be consequences!
Relax, find new single friends and secure married ones and have a blast. Enjoy your single days.
I suffered the same fate...mine was actually worse as my kids' lives were hanging in the balance and friends just made it a tad worse......
I found out YEARS later from one of my BFF's that SHE felt betrayed by me, as I had not shared with her my marriage was in trouble... She told me she used her husband being upset I had left my husband, (they were friends,) but in reality, SHE was the one who felt I hadn't confided in her about our issues. (I was one to bottle things up and not talk about it.)
If you have any issues and miss your friends, it may be as simple as being able to sit down and communicate w/ them..
Additionally, when married, we tend to have "married" friends, whereas our lives have changed. If we once went to the movies as a 4-some, now the newly single is just the 3rd wheel...