When dating, I don't think that you should always be expected to pay for everything just because you are a _____.
It's like expecting all men to pay for everything at all times when dating women just because a man typically has a lollipop. It's kind of silly and outdated because, now, many women also have equally-paying jobs and are more than financially capable of spending some pay on leisure.
If you did not mutually agree that you, as a Caregiver to this person, would take all financial responsibility when it came to dates then I think you did the right thing to split up some costs occasionally. I can't imagine you advised her to pay for a very expensive meal while you paid for a very low-cost event. If you had done something like that then, sure, maybe she felt like there was an unacceptable imbalance and dropped the idea of pursuing something more with you.
I highly doubt that she chose to end the relationship because you asked her to pay for a date. I wouldn't try to focus on that at all. I don't think you did wrong with that.
I am kind of thinking what Sweetling88 says. Maybe she wasn't as involved in the relationship as you were at that point.
Did you two agree to be monogamous or was the situation still open, labelled as casually dating, for you both see other people without discussing it with the other?
Sometimes people see "open" relationships as non-commitments.
"Over the course of 3 months I went on a few dates with this person who I seemed to have a strong connection with," is drastically different from, "I was in a committed relationship with this person for 3 months."
Maybe to her you two were casually seeing each other if you two never actually talked about it. Alternatively, maybe she felt like you two were progressing too slowly or not at all--nowadays it seems like a lot of submissives are anxious to receive collars to indicate serious long-term commitments. It's possible that she wanted things to get very serious very quickly but neglected to tell you that it was important to her (
it happens; we're human) so ended up moving on to someone else who seemed more serious to her. I'm not saying that her actions were right, but I'm just throwing possibilities out at you to consider.
I do think she sounds immature and careless to end the relationship how she did. I doubt it was a true accidental Snap, but, even if it was, it's awfully cold to respond to someone's obvious hurt feelings with, "Ok," and leave it at that. That really shows how little care she had for you, in my opinion.
Perhaps there were red flags you will eventually see in the situation though. Here are some you can think about to help possibly lead to a more realistic answer as to why she dropped you so unexpectedly:
Did you ever go to her home? If not then was there a good, valid reason or was it sketchy (perhaps she already had a commitment)?
Was she able to devote a substantial amount of time and/or effort into the relationship or did you have to plan events far out to make sure she could commit to them even though she did not indicate any clear reason as to needing to have things well planned?
Did she have platonic, get-to-know-you conversation with you frequently or did it seem all scene-based / all sex-based? Ask yourself: did you really know
who she was outside of liking to color, swing, and playfully be cutesy?
Did you ever meet any of her friends or family members? If not, was there a really good reason why you didn't?
Were you one-hundred percent certain she was older than 18?
Many minors don't take DDLG relationships seriously because they still see them as fun games instead of serious commitments--they're just young and they're still psychologically maturing.
I would work on trying to shake this off and move on, up, and forward. Try to focus on learning and growing in the DDLG scene without requiring a partner. Read a lot, learn a lot, interact a lot as friends, and eventually you're going to bump into something really great for you. You're going to be okay and you'll get through these rough patches. I'm sure you're a wonderful person who will meet up with an equally wonderful person to establish a wonderful relationship together in time.
P.S. I really (
really) don't recommend that one fet community website at all for initially establishing healthy dynamic-based relationships!