Trump is a loose cannon. Yes, he will probably get the nomination and he could have waltzed through the general election but...he is Donald Trump.
Trump needs more than half of the GOP votes to win the presidency. He could have offered Cruz a Supreme Court nomination. He says he wants an insider as VP so he could have gotten Rubio or Kasich aboard. He managed to antagonize all three. More importantly, he antagonized his rivals' supporters instead of winning their patronage.
Some Cruz people will never forgive Trump for calling their man a liar. It might not matter in the primaries but it could matter in November. This is not the same as calling Jeb a low energy guy. It is a vicious lie directed against a good man who is lived by his people. Then he orchestrated the lothario rumors. If that wasn't low enough, he attacked Heidi Cruz. You might rethink that one next autumn, smart guy.
Some men see merit in staying with their wives through thick and thin and all of her bad moods. Not every man believes in trading up for a new model every few years. I am told that some women are against the practice. My position is that discretion is the better part of everything. If a man trades up, he should not compare his new toy to the wife of a man who stayed with his bride.
The ever-irascible Ann Coulter seems to agree: From The Washington Examiner:
For Coulter, Trump's attacks on Cruz's wife may have crossed a line, and she wished he, "would be a teensy bit less low-brow."
"This is the worst thing that he has done," she said as her host laughed. "Everything else I could probably defend."
Newt Gingrich called Trump's vicious attack on Heidi Cruz as "Trump's wake-up call."
The jawbone and Twitter account of an ass might yet claim another victim.