Confess to the girl and answer, then try it.

Don’t think too much if you are not a classmate like this. I've said this to my boyfriend before. Girls are more realistic and actually hope to persevere until the end. Now that we have tried together, I won’t use you as a backup. It’s just that girls are like this, afraid that they won’t make it to the end, or that they won’t be as good as they imagined after being together.