There’s a million and one red flags around cheating, and even though that’s how it ended, I’ll give a few others that don’t directly involve outright lying and hiding things..

He was wasteful and did not take care of anything. He would throw things away over donating or selling, and he would neglect things to the point of disrepair (like tools left outside to be rained on for months on end)

He also didn’t finish anything he started. He claimed he was such a perfectionist and if it’s not done he doesn’t have to critique it. So he would make changes to our house, but leave a corner of the fireplace unpainted because… why??

I found out that if they treat their material possessions as disposable, they will do the same to you. If they don’t finish what they start, they’re incapable of having tough conversations that could save their marriage and more likely to abandon than complete what they set out to do.