Question to ponder... How is cheating achieved?
Strictly speaking, "cheating" in relationships is one partner doing some inappropriate to the relationship. But a lot of us are selfish enough to define it as the one partner doing something considered inappropriate by the other partner.
There are many reasons for outcomes to look like "cheats". But we must consider people's intensions and how much they cared about being honest, otherwise we're just coming up with things to blame.
Life is never fair. Some people hardly have control over themselves. So controlling a relationship to be text-book perfect is not the easiest thing to do.
If you see yourself getting too emotional because of your partner cheating on you, remember... Your partner too was emotional when they decided to cheat.
Take away the fuel rather than fanning away the smoke.