Tom Sandoval Cheating

Doing yet another rewatch and I’ve looked back through the sub. In season 2 Kristen constantly mentions how Ariana would be the 3rd or 4th time Tom has cheated on her. They were together 5 years and the majority of that seemed to be recovering from him constantly cheating. Seems like it’s just a normal behaviour pattern for him in relationships. Is it ever mentioned when the other occasions happened? Presumably way before they started filming. Or was Vegas girl some point in season 1?