I'm new to larger breed dogs, less than 2 years. From reading different articles I'm thinking that my male is an American Corso 20 months old and I have a 6 month old female Presa Canario. 

#1. My male has become very protective of my female. He won't let any other dogs around her or any people outside of our family. He goes into attack mode. If she isn't around or if I walk them separately he is fine. I'm wondering if I might possibly need to get rid of the female to get my male back to normal, or just continue to walk them separately. I feel that we aren't a pack if we can't walk together. 

#2. My female is showing absolutely no prey drive. She won't chase a squirrel, a bird, or anything else. Her only interest is people and other dogs. I'm I expecting to much from her or do the larger breeds take longer to get there. This is the first dog that I've ever owned that has never wanted to chase things. Everyone is telling me it's her age but I feel that a dog either has drive or they don't.