Single Parenting Support Group
Today being raised by a single parent is not uncommon. About three in ten children live in a single parent home. The most common type of single parent home is one with only a mother. However, single father homes are the fastest growing type of family situation; 60% growth in the last ten years alone.
So, I started being more social with other parents at kid friendly events. Starting random conversations and sharing parenting stories. I made new friends to hang out with and didn't have to worry about disappointing them or explaining why I couldn't do things. That might work for you, if you are willing to open yourself up to meeting new people. Hopefully your current friends will come aboard sooner than later.