Tho it seemed something bad would happen from the atmosphere of their talk, but even so thats an outcome that felt so fabricated. I mean, what she said about Yukari definitely cause it all. Sure, it could had happen by accident since she was angry, but still, after running away for three months she came back and says shes with an adult to her homophobic parents?
Also, theres plenty of ways to work around their threat, just "i wont come back" and "lets break up" is the most loserish option.
If u think objectively, although are her parents, the whole thing was unnecessary to be dealt with now. The progression as is was good enough for the story. More over, the biggest challenge left was to Yukari stop trying to convince herself shes not madly in love with Ayu. Theres was no need to complicate things like that, mostly since there wouldnt be enough time to solve it and a quick fix now would be just pointless. Anyway, it was great... until now.