Who is a true friend worth keeping and who is not? Ask yourself if your “friend” provides an abundant flow of love and never or rarely hurts your feelings. Is this person always or mostly available for you, present with you, trustworthy, and loyal? If the answer is yes, it is very safe to belief he/she is a true friend.
On the other hand, some “friends” provide only crumbs of love, typically when you meet their needs, do them a favor when asked, remember them on birthdays or support them when they need support. These folks are not shy about ignoring you when you need empathy, cancelling engagements with you at the last moment, criticizing you unnecessarily or talking negatively behind your back. They are your friend only when it is convenient for them and they get something out of it. You come last. You are not their priority. They do not check up on you with any frequency to learn how your life is going and how you feel.
Why would anyone accept meagre crumbs of love from someone whose ratio of making you feel bad greatly exceeds making you feel seen, safe, cared for, and understood? In virtually every case it stems from childhood, from growing up with one or both parents being self-centered, demanding, and even abusive. These parents make their children jump through hoops to get small crumbs of love, and teach them this way of life, a way of life that persists well into adulthood, until such time that you enter therapy to work on the problem.