My suggestion might not be well received, but here it is anyway... lol
Dog are very much a pack animal and as such, have a pecking order. They work out who is boss and as long as it's established, they're content. It's when us goofy humans step in and try to "make things fair" that they start to fight and the balance gets upset. One of them needs to be alpha... GL seems to have assumed that position. I say let her be boss and they will co-exist peacefully... encourage him to fight back and they will both be unhappy.
Repeat after me.... they are not human... they are not human...
