Bull Mastiffs and Broken Hearts

My old neighbors had a bull mastiff/Pitbull dog that adored me. We had such a tight bond and I used to see them everyday. For his birthday I bought him a special treat and I always felt like or connection was spiritual. When my neighbors moved away I stopped going to visit him because I respected the fact that he had a family. For 2 years sense I last seen him I thought about him everyday, even prayed (to this day) I got so depressed when I stopped going to see him. Yesterday I drove by their house to ask about him. They told me after I stopped going to see him, he became very depressed and would look for me. The neighbors called the SPCA because he was barking too much and 4 months after I last saw him he was put to sleep. Did he die of a broken heart?? I can’t stop crying since I heard this news. Why was he acting out of control??