That's the one who is quick to get angry.
Who doesn't apologize easily.
Who acts before thinking.
Who feels entitled to everything.
Who thinks they are doing their partner a favour.
Who thinks if the relationship ends they'd meet a better person. It could be the man or the woman.
Immature partner expresses that he/she is the one anchoring the finances at home.
Immature partner keeps malice after every misunderstanding.
Immature husband abandons food due to misunderstanding while immature wife refuses to prepare meal because of provocation.
Immature minds in marriage don't forgive and forget issues.
The immature partner always feels like he or she deserves what he or she has or even better.