I am sorry for the loss of your husband. I am mid life single through divorce.
In the 2 years or so before I actually separated from my ex, I started to quietly share with other married friends how unhappy I was. It took a lot to do this because of the culture around protecting your husbands honour and reputation, not airing dirty laundry, relationships are hard, till death do us part etc.
Almost everyone I mentioned to that I had been to marriage counselling, they admitted the same in return. There are a lot of unhappy midlife couples out there. All different reasons keep people together, finances, fear of being alone, pride etc.
This is so much more a reflection on the married couples that are leaving you out, and some level of insecurity that they have. I think it's one of 2 things:
- They don't trust their partners, or
- They are unhappy and have made so many compromises to maintain their relationship, because they have believed patriarchal BS that that is better than being single, they are projecting this onto you. They think you will also make massive compromises and must be desperate to get into a new relationship.
Friends in happy healthy relationships would not leave you out.
Friendships are often in your life for reasons or seasons. If these married people have personal issues that mean they don't include you, time for new hobbies and new friends.