The solution is simple, but not easy.
You need to work on a project that's so interesting to you that it won't matter if the girl flakes. This is hard since you still have a job (I think the best types of projects for this are business related)
Personally the times I didn't care whether a hot girl would meet with me or not, were the times I had more interesting stuff to do. For example, in December I completed my first English book. Even though I was approaching and setting up dates, I just didn't care if she'd show up. In my mind, if she flaked I'd just have more time to work on my book.
You're not missing a greater purpose, but you're definitely missing a bigger goal.