How do boys know if it's the first time for girls?

The girl didn't know anything for the first time. When making love, she won't take the initiative, won't wake up, and will only endure the pain. Well, the hymen will prevent you from entering, and it won't be particularly smooth. It doesn't necessarily bleed the first time. It depends on the strength of the man. When you enter slowly, you usually don't bleed, but you will have some pain. It will hurt for two or three days at first. Some hymens will also break when you do a lot of exercise. If you love someone, you shouldn't care.