Ok so I read it before on Google translate.
So in short
He uses her as his bed mate
She grows tired of his treatment.
Leaves him
Leap of 3-5 years
Comes back with a child
Ml scolds her thinking she cuckoled him
Misunderstanding solved
He realises he loves her
Sworns to never lose her again & treat her good
Proposes lavishly
She accepts
Spend quality time together (Snu Snu)