This is an interesting engaging game and looks like something you can expand on. I was left wishing there was another level which is a good thing.
I like the Extra Monochrome art style.
Different puzzles for different levels is great
I can definately see the connect theme coming through
Great feedback to the player
For the first puzzle I was pressing the button on the beat(which seemed like the thing to do) but it didn't work. Then tried pressing the hearts that didn't work either. Although I knew when i didn't hit it I couldn't figure out when exactly to hit it.
For the second puzzle the animation of the players falling in love was a bit to slow so I couldn't track how many many pairs I got. Maybe you could add a counter at the top so i could get score feedback realtime
I would have liked to be able to replay the level before being passed on to the next