Being boring or absent
Dogs hate being bored, want to do things and spend time with you. They can’t stand it when you’re not there because they never know when or if you’ll be back: that’s why they show great joy when you come home, even if you haven’t been out much. The worst thing, however, is when they are really abandoned because they will never understand why and it will be difficult to move on.
Don’t make your dog bored and do a lot of things with him, try to be absent as little as possible and never abandon him.