Rin has outright stated she's bi. She just mostly goes after women since that's the only thing around besides Sensei; and I think Sensei kinda friend-zoned himself with her when he turned her down during her fit of depression. She doesn't seem to think he's into her in that way judging by the conversation she has with him during the beach event while she's freaking out before confessing. I could be misremembering that or misinterpreting it though.
Oh yeah, that's right, I seem to have forgotten that since she never goes after guys while, you know, not in one of her depressed periods. I wouldn't say he did that to himself, at least not yet, he just
didn't want to take advantage of her because she is extremely vulnerable to self destructive actions in her depressed state, as we saw the first time she gets like that.
To be completely honest, is that an issue tho? Maybe i'm alone in this, but being a good homie to her is more than enough already, no need to bone her. All that matters is that she's out of the craphole of an emotional that she's in.
Also now that the new update came, i realized that every single girl in the original class has their life eff'd up one way or another, with Makoto closing out the circle. I was silently hoping that her backround as far as job goes is the most that she would dip in the eff'd up category, but now that Bluejay happened... i do hope we'll get onto fixing these lives, one by one. Although so far it seems that with who Sensei is, we're more of a final nail in the coffin than a helping hand.
Oh no, Rin definitely has a bit of D deficiency going on if you know what I mean.

I think she's going to be fine, she has support extremely close to her, even from the one she was
shot down by. I have faith she will pull through even if it takes a full class intervention to stop her going to extreme measures. Yeah, I think it is safe to say the entire cast is more or less unstable, I mean that pretty much got spelled out in
Ami's and Makoto's last events of the update. We'll get there, we're already seeing an impact with a few girls and even Sensei himself. You could be right, though, we could be that one final push everyone needs to snap completely.
It's no issue at all. Although she does kinda need to get laid with how thirsty she's been the last couple updates. I was just pointing out why I think she goes after women more than men despite saying she's bi.
As for the second half of your comment: I've said it before and I'll say it again; this is a denpa game. Things are almost certainly going to get much, MUCH, worse before they get better. IF they get better.
No, you're right, it makes sense that she would lean more toward the ladies with no men around, then one suddenly comes into her personal life and we might just see the other half of her orientation start to bloom a bit more. As far as the Denpa aspect, yeah, I'm leanig toward final nail more than savior myself. Sensei is starting to show signs of redemption, but it just isn't enough at this point.