Why would my ex stay around for so long after all that happens

This ex and I broke up a few years ago. We have remained friends and have been on and off a lot. We still talk a lot, she is the main person I text and I am sure its the case for her as well. We fight a lot over me being clingy and needy. I get in the way of her relationships cause her boyfriends don't ever like me talking to her still. Why does she stay around? People tell me its because she still really likes me but doesn't want that serious of a relationship yet but I don't want to give myself false hope