We'll eventually come to find that, after the divorce (which happened near the end of elementary school), Runa lost all contact with her mother and was in the custody of a father mostly absent due to work and a free-spirited grandmother who would disappear for long stretches to vacation with her social clubs or her boyfriends. Even Nicoru was too messed up clinging to her own lost love to be of any real help.
Yeah, your cell's screen breaking is a reason to break communication for two weeks. I mean, if only there were ways to contact someone you cared about, except of putting them through the hell of worrying for two weeks, right?
If your first instinct when hearing that she had other boyfriends in the past is to obsess over her body count, then that's really REALLY weird and you need to reevaluate your priorities in life
Well, it's weird to be obsessive about that kind of stuff, but it's not like having a lot of experience doesn't change one's perspective, and it's especially a meaningful difference when for the other party the relationship's their first.