The friend came to the party and after some difficulty came up with a way to keep the dog away from her that made it not LW’s responsibility. I get why LW didn’t like it when the friend “freaked out” over the dog wagging his tail, but I don’t understand why LW is upset about her recruiting another party guest to help. I think objecting to that is unreasonable, and I wish Prudence had said something about that. (If the party guest complained, that would be another story, but nothing was said about that.)

LW has a few choices.
1. “you’re not invited to parties at my apartment any more because I can’t handle your reaction to the dog”

2. “I don’t like how you handled the dog issue at my last party, and I’m not willing to crate the dog during parties, can we think up another solution?”

3. If it’s important to keep this whole set of people together, throw some parties outside the house so the friend can attend.

LW can probably imagine the results of each of these solutions and choose depending on how important the friend is.