The former football player explained why on Thursday's episode of The Jenny McCarthy Show.
"Honestly, I did not [watch]. I had a little PTSD," the season 23 star said, noting he did follow along on social media.
When asked to elaborate, Underwood said it was "just the frustration."
"I'm not really under contract anymore, which is great," he told the SiriusXM host. "But at the time I was. So, I couldn't really speak out, or if I got frustrated, I couldn't tweet anything. I think for me it was to avoid any temptation of pissing production off in a way. So, I just sort of took a couple steps back."
Still, Underwood said he "watched what happened" and "heard what happened."
"I obviously have social media," he continued, "and I was just frustrated for him. 'Cause there were moments, like you said, where you can tell that was set up. I'm like, 'You guys have to help him out. He's struggling somewhere. So, just set him up a little bit more for success.' So, I was more frustrated for Pete, I think."
The reality TV star admitted there are moments on the show when The Bachelor is struggling and could use some "alone time."
"There are producers; there's camera guys; there's everybody around you and you're just like, 'Can I just sit and be alone in this moment and just sort of, like, decompress and figure out what I want and what's going on?'" Underwood continued.