Baggage comes in different forms, but often it's an unhealed parental wound. We grow older but some of those wounds don't just heal up with time and age.
One is a feeling of "nothing I do is good enough." As a child, this wound was created by a parent who thought they were motivating their child by not over praising or by outright criticizing. It was meant to inspire improvement but it didn't feel that way at all. It created despair.
Another is a feeling of not being heard or not being important. This was often created by parents who were insecure as people and didn't realize how powerful their words and attention were to their children. They sought validation for their insecurity in work or from strangers and acquaintances but it was seen and felt differently to their children. It created low self worth.
When these two types of baggage meet up within a relationship, both adults turn into children again, one is convinced that nothing is good enough for their partner and the other feels like they're always taken for granted and never prioritized and not important at all. The pain is primal and real.
To heal, each must look at their own wounds and how they are projecting them onto the other. That's where the power of love, patience, and self reflection can come together in growth and result in freedom from the past, maturity, and peace within the relationship.