Why is this guy so mean to me about my virginity?

Don't do it! You're gonna regret the decision, especially since you would be doing it for an asshole guy. If he really cares for you and wants to be with you he wouldn't want you to be sleeping with other guys. And he shouldn't be putting the blame on you for "holding up" the relationship, he's the one to blame because he's asking you to do something thats unfair. Dump this guy.