I have had these problems as well. I think for much of my life I tended to be avoidant, because I was terrified of the strong emotions inside me that could lead to being insecure/obsessive.

It has got much much better, to the point I would say now it's not a major problem for me almost all of the time, and I think maybe others would not identify me as having these kinds of problems. I think it got better through long term successful therapy, which has included being quite attached to my therapist, and also other close and stable friendships.

Therapy was definitely key for me. I already had the friendships with lovely people who cared about me, before therapy, but these attachment-type problems and insecurities were always rearing their head and causing problems for me and those around me. Therapy gradually turned things around and I was able to apply what I learned in all my other relationships, also I gradually felt differently about myself and this was the key thing that has affected everything else.