PE Only While Watching Porn?

So, today I screwed up watching a porn video and ejaculated in my pants. The thing is, I was not rubbing or masturbating. It was just me watching a video and skipping through to see what the girl was saying, out of curiosity. I was watching out of curiosity, not for arousal. The video was hot, I was aroused, but I wasn't rubbing myself through my pants or anything. Nevertheless, I ejaculated, which is infuriating, because I haven't ejaculated in like a month, and was saving myself for my wife.

Anyway, this isn't the first time something like this happened, where I'm watching a porn video and can't keep myself from ejaculating. But in the prior instances, I was at least doing some rubbing and was on a porn binge.

Also, I have no PE during sex. I can last for hours. So, what's going on? Can someone help me out here?

Bonus points if you also practice QiGong or TCM and can provide insight from that perspective.