How about flower mode? There's a delicate flower and you must keep the horse from trampling it.

You get one bridge to place over a water square.

Cute idea! It feels inelegant to me, though, that the lovebirds round differs arbitrarily from the regular round—water, power-ups, portals can all change completely. It might as well be an unrelated other level. Would you consider a design principle like keeping water the same in bonus rounds?