I remember watching Lixian (Markiplier's editor) make a game with the theme for a jam. It might've not been a Brackey's Jam though.
Taken from Lixian's game posting:
"Do It For Me is a sidescroller horror platform game. The original version of this game was made for the Brackeys Game Jam #2. I decided to make a couple of improvements to the game and release it as a full game." - Lixian Games: Do It For Me (Jam version)
The Jam: Brackeys Game Jam #2 - itch.io, and yes the theme was "Love is Blind".
Yes, Love is Blind has been used before. There are some more open ended themes that encompass old themes too - Strength In Numbers (Stronger Together), Sands of Time (will end up being the same as Rewind in most cases). I hope we don't get Love is Blind, as the more variety of games generated by this event, the better.