while my friend is not diagnosed with bpd she has issues with codependency and usually fixates on one person. we got close really quickly after becoming friends and she responded quickly to my texts and enjoyed spending time with me. i later learned she had this attachment to me similar to the attachment i had to her because she told me. my moods centered around her, i took many traits of her personality and made them my own, and got obsessive about her. but then she got a boyfriend, and her issues with codependency made him everything to her and she lost that (unhealthy) connection with me because she now has that with someone else. she often neglects me and her other friends to spend time with him, and she knows this and says she cannot stop it. but she is still my favorite person, so not being hers takes a toll on me because she is still everything to me while i am of less importance to her now that she has someone new.