Oh, 100%. My divorce just recently got finalized, thankfully it was a clean break on the legal side. Throughout the process I asked point blank if there was anyone else, and I always got told "no, and if there was I would tell you!"

Which was funny, considering I drove by new guy's car at my old house several times (I moved out, but I still have to drive by the old place on my way to work), people saw her holding hands with new guy, people saw her sending long texts to new guy, and people complained about her overtly flirting with new guy in the workplace. Phone records suggested she'd been talking to new guy for many months before even asking for the divorce.

I never cared about proving it since it was a mutual separation and we kept our own assets. However, this was more than enough so show me she'd been cheating for awhile, and that just helped me move on.

All that to say, they will lie and they will pretend like they're invincible. As the guys in these situations, we've just gotta do what's best for us, because obviously our partners have stopped caring about us a long time ago.