It seems like a substantial age gap. He is 1.3 times her age, so I'd be a bit concerned tbh. I'm not sure what I'd thunk of him tbh. I'd be worried about his intentions but I'd try to talk to them both and gain their trust so that I could be sure everything were safe. This is just me though. Please don't be offended, I have a maternal streak the size of Africa, so that's just my opinion as I'm overtly protective.