So, I met this girl on tinder. Talked while she was abroad doing charity work, and when she returned, we slept with one another before she returned to her uni a few cities away. Over the course of the evening we slept together, she made the hard sell that we could be an item, and following her departure, I did like the idea of us being together in all honesty and entertained the thought. I would then let her know that a couple of dates would be nice to get to know her better, and she agreed. However, she informs me this morning that she's "low-key seeing someone." I did feel upset, a bit manipulated, but I'm more so frustrated that I allowed myself to become hopeful about sharing something with her. I felt vulnerable and I hated it. Is this overprotective approach to making myself emotionally vulnerable to others dangerous? Are the emotions I am feeling valid? Should I just cut her out of my life outright?