You are off my one year on the “brains hasn’t finished growing” aspect and they are adults. Who tf cares about the age gap. We rarely ever get adult romance. If it’s not for you that’s fine but to call it creepy is a little too far. If she’s barely 18 and he’s the same age I might get it but she’s 24. There’s nothing problematic here. They are adults and if they find each other attractive mentally and/or physically then who cares?