well, not surprised. It was bound to happen since the start : It was too soon for Hiromi and Lili was not experienced/mature enough to handle this. They are both at fault in this mess. Their dynamic was awful from the start.
And he must go out with the other girls too

.
More seriously, until he sort out everything in his head, it'll repeat again. Well, at least I'm certain he'll reflect later on his own issue.
For Lili, I think too she'll leave the house. It'll be so awkward for both of them. Plus, she'll need to focus more on her art with how thing will progress now.
And I bet it'll happen for every girls, save for the destined one.