Please immediately stop asking yourself what more you could have done for the guest - I’m sure it had nothing to do with you, that this was simply ”that kind of guest”.
The good thing is that their written review was great, as are your other reviews. So they only hurt your overall rating, which will not take too long to fix (do the maths).
4.75 after 4 bookings might affect you a bit in search rank, but not too badly. And as soon as a guest sees your reviews, they will not worry about the average rating.
Giving up because of this, would be a serious overreaction. 😉