Stop
Stop.
He'll moan like hell until you resume (or beg, promise, sulk, force you, etc.)
Seriously, a guy doesn't have to moan to be very happy indeed. If he is going to moan it will be due to...
Yes, guys moan during sex. This is called an orgasm and more often or not the boy will then produce "cum". Boys don't moan as loud as girls because the female have more nerves in their genital...