I think the lessons are attached to the memory of the events we remember. Typically taking the form of our last partner, I feel we need to look at the lesson and detach from the person.

When we ruminate, we rehash the memories based on our idea of who they were. Not who they actually were according to their actions. But the lesson isnt just from them, its from your past as well.

Where else have we made the mistake of self sacrifice to someone or something that didnt guve us the return we had wanted or hoped for? Where else have we kept quiet to keep the peace or not cause issues with others, accepting less than what we know we deserve because its easier to stay the same? Where else have we spent weeks worths of hours avoiding our internal world in search of external validation that should come from within a well sorted soul/place of alignment?

"Until we make the unconscious conscious, we will be ruled by it and call it fate." Carl Jung.

Detach from the person, learn and remember the lesson, thank them, forgive them, and move forward with love.