It's a bad idea, right?

Monoma Neito is in love.
He tells as such to Uraraka.
The catch?
It is not with her.
Monoma Neito is totally, madly, and crazily in love with Shinsou Hitoshi.
The problem? Shinsou is a dumbass that doesn't understand love confessions and is as unaware as a brick.
Desperate times call for desperate measures, so Monoma asks Uraraka to be his fake girlfriend, to make Shinsou jealous.
If he is in fact, also in love with Monoma.
She says yes because she likes to help people in need and he offers her mochi. No one says no to mochi.
She had no idea this proposition would unravel a chain of events that would lead to other people being jealous.
Of her.
What could possibly go wrong?