I'm 28, and currently studying for my second degree after a career change. When I went to university at 19 I struggled with making friends and isolated myself a lot and felt really lonely there.
I'm now 28, and struggling once again! There are people on my course who I'm friendly with, but I never want to approach others in case they don't want me sitting with them, or if they have saved the seat for someone else. I tend to go in and sit towards the back and hope someone sits next to me. I also struggle when we have breaks in between lectures, as I will go and sit in the common room on my own, despite it being full of people I know - I'll only go and sit with them if I'm actually invited otherwise I presume I'm not wanted.
There are other mature students on the course, but they all have children and seem to be at a later stage of life than me, despite being around the same age. I think I am slightly young/immature for my age.