For those who have a Vision Cam:
1. Scan in 7 eggs of a certain piñata.
2. While waiting for them to hatch, have their home built.
3. Once they start to hatch, pick two of them and fulfill the other romance requirements.
4. Once those 2 are ready to romance, have them meet up and start the mini-game.
5. Get through the mini game with a good time. It's okay to die and start over.
Doing this sped things up quite a bit, as I only had to do each romance mini-game once. (I got twins every single time this way, except for once when I got a horrible time on the mini-game.)
Oh, and I used the same 10 piñatas as outlined in Cosmic Katamari's solution (except i used Bunnycomb instead of MooJoo)
Hopefully this is helpful!