Hi Elizabeth,
Some guys get excited very early when chatting with a girl they like on a dating site and quickly ask to hang out after only a few messages with her.
Guys don’t receive anywhere near as much attention on a dating site as women do. Once some of them start chatting with a girl they like and it is going well, they quickly ask to hang out in the hopes of keeping her from the competition.
Instead of unmatching so quickly, think about letting him know that you would like to get to know him better before meeting in person. This is especially true if, up until that point, you had been having a good conversation with him.
If he is only interested in hooking up, he disappears anyway and you don’t have to worry about his intentions. If he has good intentions, he respects your request and conversation continues to flow naturally.