Help me!

I have recently started dating again. He's 18, I'm 16 and he's the sweetest thing, I've never had an issues with him, we've been dating for almost a month and my mom is not open to letting me hang out with him, we haven't done anything and don't plan on doing anything and I've tried to tell her that. My ex boyfriend was very abusve, but before she knew that she was open to letting me go over to his house. Any idea why she's not so open now?