Women lie/cheat/steal just as much as they accuse us [men] for. So don't take it personally. They just weren't good enough for you. Where they stray, your Z will never stray. Unless someone else just happens to have your key fob frequency.
But in all seriousness, sorry to hear it (especially as a 4-peat). Just don't internalize it. It's not your fault or a difficiency in you that makes them unfaithful. It's them.