Feeling bad about yourself

Yesterday I got a birthday gift from one of my school colleges. I am graduted now. Long storu short that we were in the sane school then got to same college but different departments. The relation between us was nice but not that intimate. I have a closer relationship with her younger sister, who got me the gift and my clollege participated in. I knid of wonder would she bring me something if it werenfor he sister. But what I really hate myself for is that I didn't even tell her happy birthday at hers back in January. I feel people are loving me and wanting to have a relationship with me, but I am very bad at it, weither it is because I forget and bad at it at general, or because I used to have so strict rules or expectations of what I want from them. I really hate myself for not giving them the same care and love they give me. Or think about them as they think about me