Generally speaking, an emotionally connected affair is more painful to your betrayed spouse than a one-night stand. This is because, from your betrayed partner’s perspective, longer-term affairs undercut everything that happened in your relationship while the affair was taking place.
Essentially, if/when your mate learns you’ve been sleeping with someone else for the last decade, he or she wonders, “All those times that you told me you loved me, and that you loved our kids and our life together, did you mean any of it? Or was it all just a lie?”
So, as you can see, there are many factors that can make sexual infidelity “worse.” That said, all cheating is painful to your betrayed partner. And all cheating will strain your relationship. Furthermore, most of the time—and I can’t stress this enough—it’s typically not the sex that’s most upsetting to a betrayed partner. It’s the constant lying and the keeping of important secrets.
As such, the process of healing from infidelity is typically focused as much on restoring relationship trust as on stopping the cheater’s sextracurricular behaviors.