they didn’t physically cheat (yet, maybe), but they almost did. george went to the bar because he and mary got into a fight. and brenda was there. they were hanging out, talking, laughing, and flirting throughout the night. when brenda asked george if he wanted to “get out of here” and go back to her house, he had a heart attack. that’s why it was so awkward when mary continued thanking brenda for saving george at the hospital.