My ex-husband did this to me last August after 37 years of dating, marriage, breaking up, and reuniting. He was too cowardly to tell me he had been seeing someone else. So let's not just blame the millennials for their modern break-up techniques :-) Baby Boomers can be just as bad. And just like your friend, I could never get out of him why he said goodbye let alone in a text! My son told me a month later. Surprise, mom! But, it did not go well for my ex. He tried to come back in October, but I was reluctant. He fell apart after that, relapsed (alcoholic), and got his 4th OVI. I could say, "that's what you get for saying goodbye to me in a text, you scummy coward but I stayed quiet and maintained my dignity. He's in jail for a long time now.