Karen is attracted to Matt so she’s been watching him and paying quite a bit of attention to him and suddenly something clicks and she thinks of all of Matt and Foggys interactions and realises that Matt is in love with Foggy,

She is jealous and hurt for all of 5 seconds then she’s just thinks how adorable they would be together and decides to make it so.

Bonus Foggy loves Matt too but he just thinks he has a man-crush on him.

Also I am totally fine if this ends up having completely ridiculous matchmaking scenarios happen.