Married couples depend upon each other in many different ways, and it affects how they socialize with friends and family. Those who have found their relationship crumbling might decide to get a divorce, and they then have to come with life when they become suddenly single again. Those friends they rejected from their former life might now seem more attractive, but it could be that they will be less than forgiving when they were previously ignored.
A person who has been in a marriage often experiences a time of isolation from single friends because they are missing an important element, but there are good ways to handle the situation. The unmarried friend might not be good to invite to a couples night, but rejecting them completely could ruin the entire friendship. Those who are married might believe dumping a single friend is okay, but they should understand what they are giving up.
When a person gets divorced, support from other people is part of what helps them begin their life again. Those who snubbed their single friends in favor of married couples might find those couples rejecting them, so they will turn to their former friends who were not married. While it would be nice to receive instant forgiveness, hurt feelings or a lack of connection could keep their former friend from reconnecting with them. It is less about getting back at a person and more about having moved on in life after being rejected.
There is no reason to push single friends away when a person is married, but it is something that often occurs. People believe their time should be spent only with those who are in the same type of committed relationship, but they could find that rejecting single friends will eventually make them feel lonely when their own relationship ends.