A newbie here that started to familiarize myself and learn about dogs world/psycohology very recently to help train/understand my wife's extremely-spoiled 4 years' Griffon male.

A bit of context:

I just got married 5 months ago, and my wife has a 4-year-old, extremely spoiled, untrained Griffon male.

She loves him insanely, which is understood. She knows nothing about dog training and her dog is so spoiled and connected with her to the extent that he’s, almost, not loved by anyone except her. I know nothing about dogs. I'm actually a cat person and I have a cat, he is 14 years old. Before we got married, I had to leave him at my mum's since I knew that dogs and cats cannot live with each other, especially if one of them is very and they were not raised up together. I know dogs and cats have nothing in common. They're completely different creatures, and I've started to watch YouTube videos about crate training, leash pulling, barking, basic obedience, positive reinforcement, and so on.

The thing is:

Since we got married, I started to walk the dog almost on daily basis, do a bit of playing and training using treats through corrections and reinforcement. Sometimes, he shows signs of aggression through this growling towards me and even sometimes towards my wife, his owner. and showing teeth, which I correct, immediately, by striking him which he then backs off right away the last time he did this, i stroke him multiple times. I wouldn’t say he’s a different dog now, but we have started noticing positive changes on his attitude like less barking, respecting boundaries a bit, complying to a few orders and so on.

However…

Very Recently, he started showing very weird mixed signals towards me. Such as, he would greet me and jump happily when I get home or wakeup, yet 5 minutes after he would be following my wife and stand by her leg as she’s standing in the kitchen, in a weird way like he’s afraid of me or avoiding me for example. An hour later, he would come and sleep on my lap for a couple of hours.

I don’t know what’s wrong or what this means. Can you advise, please? What to do to make him stop this? If this is even a thing?

Expert Advice Needed on griffon Behavior for a Newbie