"Some dogs are shy at first. it takes time but some do open up over time and play with other dogs," shared one user.

The tale of a once-standoffish elderly rescue dog who struck up an unlikely friendship with a treats-hauling mailman before she died has gone viral, thanks to a tear-jerking tweet.

Why are you still friends with creeps like this? DEAR ABBY : My younger brother, “Paul,” is 40 and in a rut. He had been friends with a friend of mine, “Mitch,” whom I met in college.

This friendship between a mailman and a rescue dog is breaking the internet's heart. This is the story behind that viral, heartbreaking Twitter post. By Catherine Thorbecke.