This sounds repetitive, however, it's not. The thing that's different is I know, I know it's a mistake and I want to help her. She wants to go somewhere for a guy she met online, and she's fallen in this I-think-I'm-in-love things before, and she got hurt. However, she thinks this one is THE one. I told her to trust me and she did, but now the guy she's with is upset, therefore upsetting her. I told her if he's not going to take a chance and come see her instead he's just not that into her. But now I feel bad, did I have a right to stop her? Should I have done that?

You absolutely had a right to stop her. One of the most dangerous situations to be in, is going to meet someone you meet on line.

Ms tickle

If she chooses to meet him it should be done in a very public place. Maybe bring a friend along (maybe you) but she should not rush into anything. She doesn't really know him. I can tell you I have the body of pamela anderson... I'd be lying, but you would not know this.

You did the right thing,if she still persists and wants to see this guy,go with her,and meet in a public place,don't leave them, you can keep your distance but in eyesight,but let him know your around,if he is really into her,he will understand your concerns.

I told her to trust me and she did, but now the guy she's with is upset, therefore upsetting her. I told her if he's not going to take a chance and come see her instead he's just not that into her. But now I feel bad, did I have a right to stop her? Should I have done that?

Are you saying she has a boyfriend but wants to meet this other guy?
If she is upset with her boyfriend then she needs to either put her efforts into working it out OR break it off with him before she goes trapsing off to meet some chat room guy.

The others are right and IF she ever does decide she is going to go meet some guy it is best that she does take a friend along. It should intimidate any one that had bad motives because they automatically realize there's a change in plans now that she is not alone.