but if it does not work after the test drive, your first time will be gone.

Plus, test drive what? you can tell by other behaviors related to sex, instead of intercourse, which is more dangerous.

But before he met me, he had sex with a few other girls. Even if he has no disease, even if using condom, we can not make sure it is safe. What if some bad things happened, who will be responsible for this. I've also heard it is very easy to get female problems if you have sex too often, or not in a correct way, or non-clean sex, which we can not be 100% sure.

I just don't know how people can treat sex so casual. After all, it is directly related to your health.