I have a maltese and he seems to be lost

which is ok with me. I know I am supposed to keep my Yorkie female who is in heat away from him but its almost impossible

I am having a hard time. I dont want her to have his puppies (morkies,yortese) they would probably be precious, but I dont want them
I just let them out together to go potty while I am standing there and he starts sniffing her and she lets him and he tries to hump her only he is doing her head. She seems to not be interested in him at all

but she does let him hump her hear, I have been trying to keep them apart believe
Oh yeah one more thing she is normally spoiled but she seems more clingy now, since she went into heat