With Finn's status, he was not worthy of the wealthy Monica. Therefore, once he felt that Monica did not love him, he would turn around and leave.
This was the influence that a foster family brought to the child.
From then on, Finn withdrew from Monica's world.
Even during the period when Micheal pursued Monica, during the period when Monica still clearly loved Finn, Finn never appeared in Monica's world again. Therefore, it was not difficult for him to pursue Monica.
As long as he gave her happiness, as long as he made her happy enough to forget Finn, their relationship would last.
They dated for two years.
Finally, his father found out.
His father mercilessly urged them to break up.