If you want to keep here than you will do something about her.If you don't, then just pretend like nothings happened and if she insist to see you again give her your number but with last digit changed.About how to identify and avoid girls/women who want long term relation ship I will say few words later.
In short: she must be not scared from you and she must have sense of slight control over you, so do everything you can to assure that she see you on that way.If you read carefully, than it is clear that girls like no-obligated adventures, one night stands, flirting and everything as we do, just are more frighten and more careful.You will easier hookup girl online, than in supermarket, but it is not impossible to act also in situations where you are very tight with time.Be creative, and act adopted to situation,start from easier places and when you get some confidential you will easy recognize when and what to say or do.First rule is to see that you are trust-able person.
That means that you are not some offender or abuser, that you may go out of here life easy if she don't like you or stay in her life if she likes you.
Your role is to look like someone who will not make troubles, will not fail in love if they are in marriage and make problems, you just need to look like "Ok, we can have sex tonight, but if you don't want, that is OK too".
For girls, like it should be to you too, online partner finding, is nothing special, just one more way to get dating or sex partners for 1 night stands or LTR.
Personally, I think that mostly of women (especially when they are younger) really don't knows what they want from life, from you, from self, so why would we bother with that at all?
Ask yourself, how many times you felt in love attracted by gorges girl and tried to do everything for her in hope that she will feel and act on same way, and did she felt like you?
In most cases answer is: No, so lets focus on our wishes and feelings.