So why do people cheat? Ultimately, people cheat because their needs are not being met, whether these are emotional, relational, or sexual needs. That's the number one reason that people give for cheating. Of course, we don't know whether these reasons are also excuses that people come up with afterwards when researchers are asking them Maybe sometimes it's pure indulgence for some people. Some people are hedonists and they believe in seeking out pleasure and pleasure above all. Some people are sociopathic narcissists and they simply don't care; they don't have guilt or remorse and they take whatever comes their way. So, people cheat for a variety of reasons.
However, most commonly given reasons are unmet needs in the relationship. So, if you're not being heard, if you're being unappreciated, if you're emotionally abused, if you're ignored, if you're feeling taken for granted - that's a big one - you will be more predisposed to cheat. If your sex life has dried up, if it seems like you're not really connecting anymore or if it unsatisfying and somebody else comes along who seems exciting and interesting and sexually attractive, of course, you would be prone to cheat as well. And morality, religiosity, all of those things also play into the desire to cheat as well. And cultural norms, if you're in a culture that's more permissive about polyamory, perhaps you're more likely as well to be open to infidelity. So, there is not one reason.
However, to avoid cheating, look for unmet needs and negotiate, compromise, talk about them, communicate as much as possible because a lot of partners are willing to actually meet their partner's needs if that partner just lets them know that, "This is what I need. I need more hugs, I need more compliments, I need to be dating, I need more courtship, I need more attention," you know, "perhaps I want to try something different sexually, I wanna be a little more adventuresome," And communicating those needs to your partner is paramount to keeping your relationship vital and alive.