I know that a lot of guys are just going to say the woman was wrong she never should have...but she got a one-off, while Lance been bagging hoes since they met and never stopped.
Lance is the guilty party. He was a man-whore whose reckless behavior risked a beautiful relationship.
Mia was going to leave Lance. They made it seem as if Harper banged Mia, but Mia took that D from Harper. She wasnt taking no for an answer that night. She needed to get even or she was leaving. You ever bagged a chick, but she really bagged you?
When she was praising him for saving their relationship, she was not lying. She needed that 'get back' or she was going to walk out on everything, the money, the contract, everything. That didn't matter. That wasn't why she was there.
Mia cheating on Lance actually saved their marriage, because she was leaving otherwise. Because she did that, they had a bunch of beautiful kids and 15 good years
He cheated on her a hundred times, she cheated on him once. And that one was worth 100 like when Mike got Alicia's number in The Wood. He even admitted that if she got one in on him he would have to forgive her.
To me, it's cause and effect. Had Lance not bagged all those hoes, Mia never would have fucked Harper.