Why? i feel like it'd be far more awkward for people to dodge the topic around me, especially if they were obvious about it or clearly uncomfortable trying to keep me from getting triggered. When you talk about something like that it starts to lose it's power over you. I imagine that she and the MC are pretty close as well as others are asking why they aren't dating yet and she actually felt as though she could bring it up so bluntly to him, even crying while talking about it which would indicate she has a strong emotional attachment to him.
I was also there ten years ago. When it's recent you are so hurt and angry at everyone around you, that it will always make you uncomfortable no matter how people choose to bring it up, but I think it's better to talk about it just the same, and for a while just put up with the discomfort, because it's a start to facing the stuff that made you do it in the first place, and also to recognizing the hurt your attempt has caused other people (which is sth you will have to understand sooner or later). Once you do, everything becomes better, I think. With time even the shame and discomfort wear off as you forgive yourself as well as others. The one advantage is many people start dropping their masks around you and to open up about their own problems, so you get the chance to build more meaningful friendships and relationships.
I'm kind of conflicted with how the girl handled bringing up the suicide attempt... as I've been there, I would have felt attacked rather than anything good or appreciative and would probably have a hard time talking to her for awhile.