English is not my first language, so I'm sorry for any mistakes.

So I (23f) have been friends with a girl (22f) for almost 16 years. We went to preschool together and to the school together for 3 years. I got transferred cuz of the family situation, but we kept in touch and always spend time with each other when we could.

She always had trouble making friends, she is very shy and introverted, during school years (when I wasn't around) she made one friend (who she is now not talking to) and two friends during university (one is still talking to her occasionally, the other turned out be ah). So she basically has one friend in me. I've tried to make her a part of my friend group (school friends plus the ones from college), but she feels out of place, like she can't talk to anyone (my friends and she have some common interests, otherwise I wouldn't even hope that she could connect with them), she feels like she is interfering.

I've tried a lot of times (during my birthdays, get-togethers, I've always welcomed her and she sometimes participated).

During my 18th birthday, she just left the group and went to seat elsewhere, tho I've tried to include her in every conversation and activity. She always tells me how she will end up alone without friends and with cats.

Today tho, she told that her winter depression is still there (it's spring outside and the sun is shining, so she thought it will go away) and it's not going anywhere. I told her that until she changed her mindset ( that she will die alone) she will be depressed and lonely. I told her to join youth groups of interest, to find new friends. She didn't react very well, and now she is crying. And idk if I'm being harsh or not, but I'm tired of hearing her complain about being alone then she could do something about the situation. I think that I have her best interests in mind, she's to have some other friends. I've told her that if she will not change her view, will not face her fears (meeting other ppl) she will end up alone. Idk how else to push her to pursue relationships with other ppl.