Why is damis concerned about his sister's engagement to valere?

Damis is infatuated with Valere's sister and trusts that he won't have the capacity to court and wed her if Marian does not marry Valere.  

Explanation:

Once more, there's discussion of marriage as a collusion. More critical, notwithstanding, is Orgon's declaration of paternal expert. Mariane and Valère might be bound together by affection, yet their bond is dependent upon Orgon's consent. Damis:  

"Sound him about my sister's wedding, requests.  

I believe Tartuffe's against it, and that he's  

Been asking Father to pull back his approval.