Animals do it by extra-pairing. In humans, we call it adultery or cheating. Right or wrong it is your call.
It is all in our chemistry. If you want to go romantic, then it is dopamine. Sex? It's testosterone in both men and women.
Religions have tried hard to eradicate it. They have been trying to do so for two thousand years, or more. To no avail. humans will forever be shackled to their chemistry.
Lawsuits have been filed against organized religion. On their ranks. A slap on their wrists only. If you live in a glass house...
Monogamy has struggled against it with devastating effects. Lust is irrevocable. It is here to stay. So why keep the hypocrisy?
Sure you many not agree with the above. That is not important. What is, though, is the understanding that your significant other will roam - if it is with their eyes and there is nothing you can do about it. You do the same.