Seems to be a common thing. I’m feeling it really badly at the monent, I really can’t see me ever getting over the intense feelings I have for my ex. I’m not sure I even want to. Been thinking loads about ‘why’ this intense feeling of pain is part of the human condition, and have considered everything from evolutionary biology to the cultural genesis of courtly/romantic love in the early medieval era.
But the fact remains that for most of human history, ‘bonding’ has been the default mode for life relationships, and the modern idea of multiple relationships/serial monogamy is an anomaly.
Maybe human being are just wired to bond with someone that we have sex with, and it’s our modern culture of treating people like disposable objects that is unhealthy.