What, in your eyes, would be the worst thing that can happen to the reigisa relationship, besides breaking up?
Never getting together during high school, I think. I'm almost finished reading brumalbreeze's Ten Paces From You and it is destroying me increasingly with each chapter. The story deals with missed opportunities and regret, about what would happen if the boys had never been honest with each other about their feelings in high school and moving on as things change over the years.
Perhaps this is the worst to me because it almost happened in my life (I almost let my gf go because I was too scared to confront my sexuality, but now we've been together almost 3 years). Or perhaps it's because this Eternal Summer depression is setting in, realizing the crew is going to be ripped apart.
There won't be second chances to Rei and Nagisa to get together again after high school. This is their time together, and it's their time to make a choice of what their relationship consists of. In and outside of canon, never coming clean will be the worst thing they do. They're at a point in their lives where they can take one another's attention, affection, and presence for granted, but they will come to a point (like Haru/Rin/Makoto have to now) where they'll have to confront themselves and decide what and who they want their futures to consist of.
The VAs have said before that they see Rei and Nagisa as people who will never separate, but I want this to be true. And I honestly just want them to admit their obvious feelings to themselves and each other!
I hope I answered this question correctly!