|I don't know if you still want an answer to your question, but it's a tragedy because:
1 - a lot of bad relationships and breakups (and a couple good ones too, of course!)
Spoiler (mouse over to view)
not everyone ends up with the person they (and the readers!) wanted to end up with, meaning not a happy ending for everyone
If you like most of Mizushiro Setona's pieces, you'll probably like this one too.