I have the feeling that both men and women are just feeling their way, particularly in the Reddit age range. The younger me really feared and hated rejection: it hurts, after all. But after being rejected many times, and doing some rejecting of my own (that made me feel bad, too), one learns that it doesn't actually kill you. You get over it.

You get over it to the point where you can easily remain friends with someone who doesn't find you attractive. They just don't, that's all. <shrug> It is the actions of the attracted person that leads to a toxic outcome. An approach of "hey, bb u wan sum fuck?" is toxic. So is, "I'm madly desperately in love with you. Marry me and have my children" isn't much better. But to someone you like and have known for a little while, there is absolutely nothing wrong with saying lightly, "hey, you are very attractive to me. Does that bother you?" Lightly. Lightly. Lightly. Really. It isn't the end of the world for you or for her.

If she says, "Doesn't bother me, but I don't really feel there is much potential for us that way." Then smile and say "That's okay, too. I hope you think we can still be friends." Never bring it up again, and never show it is a big deal to you, even if it is. The hurt will go away, and it will go away much faster if you don't reinforce it by glooming around like Ophelia.

Several of my closest women friends are people I dated casually, expressed interest in, and was told "no". Others are women I just didn't feel it with. It's better to have more friends of any gender than to have fewer. I have quite a few gay male friends, some of whom found me attractive. Doesn't mean they were creepy, or that they have to hate me now, I just don't feel that way.

TL;DR. Relax. Take it easy. It's going to happen to you (both ways) lots of times. You get used to it.