Resource Guarding is usually seen over people, toys and food. Even after training, do not expect the dog to stop this behavior. You have to stop the behavior by first anticipating it, and being acutely aware of it (your dog’s behavior and body language). Then stopping it in its tracks with a correction.
Things to look for in your dog’s body language—running over to you, putting himself/herself between you and another person, nudging, growling, snapping at another person/dog/child. More severe issues include attacking over a toy, food, water or other resource. The human always controls ALL resources and always corrects the dog for naughty thoughts (any of the above mentioned behaviors warrant a correction). There is a lot of misinformation on the internet that says if you correct a dog when he/she growls, the dog will immediately bite. This is wrong information and it gets a lot of people stuck. By not correcting a growl, you are allowing the behavior to become ingrained in the dog.
Sometimes guarding behavior will go away with training, but other times it’s a management issue for the life of the dog. It depends on how long the behavior has been going on and the age of the dog, how structured the dog’s life is (no resources available unless you provide them), and also how disciplined you are with your dog.
Just remember for some dogs, the behavior is dangerous and warrants a permission-based lifestyle. That means you control everything all the time. No toys or food should be left out, and if affection is the problem, only you can dole that out. If affection is an issue, you have created the problem, so take ownership. Then you have to curb the love and give it in more constructive ways, like in the form of structured play, walks, hikes, and place time. These are all healthy ways to replace affection.
One final caveat: some dogs are a serious danger over resources and have attacked their owners and put them in the hospital. These dogs are like recovering addicts and should never be allowed to have resources that trigger them. And if you do own a dog like this, you have some serious thinking to do on whether your dog should remain in your home, or possibly put down.