As far as I know from the pre-serialization, and the little bit of this that's been tl'd into en, he's basically someone she just met when feeling down. I don't believe it was explicitly stated in either (as of yet anyway) though I'd need to reread the last chunk of chapters to be certain I didn't miss a detail months ago- but I'm hoping to see a couple more new tl'd chs and then start a fresh rereading of it from the start again.