No, I don't think she did, and we don't have any evidence to support it either.
Hard as it may seem to believe, Suzanne actually seemed to genuinely care about Lucas, and if the video recordings we have of them together are anything to go on, they share the same moronic sense of humor, at least.
The reality is actually quite a bit worse than if Suzanne had actually cheated on Lucas, because Suzanne was the only real, functioning relationship Lucas has ever had, and likely, the only real relationship he'll EVER have... And he messed it up, in spectacular fashion. Lucas's one chance at happiness, waving goodbye. And after they separated, boy, he really knew he'd fucked up, too. He tried desperately to get her back. The Monday morning quarterbacking gloss that Lucas put on their separation, as if he was no longer interested in her, and initiated the breakup, is pure cope.
Obviously Lucas lies, and nobody believes that "scooting a glass on a table" in a restaurant was why she decided to end things; if Suzanne had to make a rule about no violence with lucas, that strongly suggests that there had already BEEN violence, which she had tolerated, provided he change... Which he clearly was unable or unwilling to do.
No, Suzanne was exactly what Lucas has always wanted, minus the jailbait: she let him stay home and eat, and do nothing, provided he clean a tiny bit, which he was also unable to do. In one of his angry diatribes telling younger men to pursue older women, he emphasizes that he could never even do ONE THING WRONG! Or she would leave him. Apparently, she had to leave him notes, telling him to clean the microwave, and had to remind him to wipe his ass, take showers, and use deodorant. We've all seen the photographic evidence of her shaving him on the toilet, something they don't even do at Mallon.
Nope, Lucas had actually ACHIEVED his socialist paradise, his infantalized sloth kingdom, with Suzanne... But he messed it ALL up.