History is powerful because it contains more than time.
It contains your firsts. Your private jokes. The people who know you as a pair. The home you created. The version of yourself that existed beside this person. Perhaps children, businesses, grief, family, immigration, faith, mortgages or years of ordinary life.
So when somebody asks, "Should I stay because we have history?", they are rarely asking whether history matters.
Of course it matters.
The harder question is whether history is evidence for the future.
Sometimes it is.
Sometimes it is only evidence that the relationship has lasted.
Time invested is not a reason by itself
Imagine you spent five years building a business and then discovered the business model no longer worked.
Those five years would still matter.