The only reason why I feel like the suicide theory might not be the one (cause honestly I've been guessing this for a while, since it's the one thing that could fluctuate so easily based on Tarou), is Itsuki refusing to tell them what her current future looks like. It's not like he hasn't seen it, he just feels like telling them will move the target. If he saw her kill herself, I think he'd be a little more inclined to open up at least vaguely since we now have some dangerous mentality on the menu.
Unless Itsuki is an idiot, and yeah, I guess he is. So we'll see.