Valère comes in, looking concerned. He's heard that Mariane is supposed to marry Tartuffe now, and he wants some answers.
Mariane gets him up to speed.
When Valère asks Mariane what she's going to do, she's reluctant to tell him.
Eventually, she says, she doesn't know what she's going to do.
Valère, clearly annoyed, tells her to go ahead and marry Tartuffe.
Mariane tells him that of course she'll follow his advice. The two continue fighting – for no reason in particular – while Dorine watches.
Valère says he knows that Mariane never really loved him, and that, like, whatever, he doesn't need her. He can get some loving just like that, Mariane'll see soon enough. Turns out there's some kind of "mystery woman" waiting in the wings for him.
Of course, when Mariane calls his bluff and tells him to get lost, Valère pretends not to hear her.
At this point, Dorine has had enough, and she tells the both of them to get their acts together. She gets them to put aside their silly, totally made-up problems, at least long enough to discuss the whole Orgon-Tartuffe problem.
Dorine tells Mariane to pretend to play along with her father's plan, but to find anyway possible to delay the proceedings-- faking sick, seeing bad omens etc.
Valère, on the other hand, has to go tell his friends what's up and try to get them to pressure Orgon. Oh, and they'll get Damis and Elmire on their side too.
With everything settled, Mariane and Valère finally kiss and make up.
Dorine has to forcibly separate them before things get out of control.