AnnirasSweets led me to PikaSquirrel's actual post about the pink Lovecupine goal. Since that post (with the Wedding quest) was released at Valentine's, I bet you're right and the Lovecupine sneaks in around V-day on its' own. Do you suppose you could add it to the Goal Guide separately, as a kind of "random," even though it's not technically storyline? but rather possibly just a Feb surprise? Here's a snapshot of PikaSquirrel's post which I linked.
Attachment 58744
Edit: I guess we'd really need to know what triggered it. I wonder if Belladonna
got the task at Valentine's or when she somewhere acquired a "pink" animal? Or maybe I've misunderstood and she hasn't gotten the task but expects it?