One of the reasons is that as an adult our interactions begin to shift. We are no longer in a school setting which places us around the same group each day. There are many who work from home and don’t have a staff of coworkers to engage with.
The fact is it takes work to make and keep friendships as an adult. We must consistently call, network and join groups to be around others. This takes some effort but it is worth the process.
In my own life, I have many childhood friends. We all live in different areas so we do not see each other as often as we would hope. I speak with them and have learned to take my own advice. I have recently joined a spiritual group to meet others. I will be attending several networking events to meet friends in my area. I go out to eat, am friendly and make an effort to create real world relationships.
We never have to be alone. When you face a mental illness, there are many who feel worthless. It is important to build up your own self esteem and not be afraid to connect with new people. I would suggest trying a free support group if you are still in the early stages of recovery. You may find these groups are filled with others who have been dealing with their mental health and are honest and open about their lives.
The both offer free support groups located in many communities. Their website offers a directory and details of the many free resources they provide.