This jumped out at me from your comments: "I learnt the social forms, but that's not the plane I exist on. It's a very artificial layer for me."

It could be that people did/do like you but that you did not/do not recognize it. I do think it becomes harder to make new friends the older one gets. People get busy with their own lives and I think their attitudes start to become set about so many things. As a divorced woman, I find it very difficult in real life to be friends with married women and couples. They're so busy and have so many obligations! Most of my friends are much younger than I am. Have you considered seeking out mentoring relationships? I can see that you felt taken advantage of in the past, but I have found my friendships with younger people very rewarding, and we have learned from each other, and actually have fun in our differences.