An 18 & 43 year old ?! 😩

So my best friend finally introduced me to her boyfriend and HE’S 43. I know it’s technically legal but something just doesn’t feel right. I’ve only met him once but as far as I can tell he’s not very respectful to her. I’m afraid he’s using her just for his own personal needs and doesn’t actually love her. I mean come on?! What could an 18 year old have in common with a 43 year old? My friend hasn’t even been an adult for a full year! I’m kind of worried 😭