This situation is different.
Marichiko is secretly in love with Undertoad and UT knows it!
Mari, OTOH, knows that she could never come between Undertoad and his first love ...
The Cellar.
UT is torn between two lovers [Mari and The Cellar], feeling like a fool, and as xoB pointed out they're breaking all the rules.
After banning marichiko; then; reinstating her ...
... Undertoad knows that breaking up is hard to do.
This is The Cellar presentation of
Fatal Attraction.
I'M RIVETED! 