One of Woofio's dialogues has him talk about Yaichi, and comments his concern about how easily Yaichi came around to him after giving him candy, even warning Yaichi to not be tricked by free things. If you know the circumstances behind his backstory, Woofio's reaction makes a lot more sense: that kind of situation was how he ended up as a living dog suit.
Choosing to not marry Woofio for his final event leads to him and the farmer being friends for life and he seems very happy about this. This makes sense, as the farmer is likely the first person in a long time to have become Woofio's friend and didn't abandon him when learning about his condition. He probably is ecstatic to have a true companion in the farmer now.
