Will it affect my fathers case (where I am the petitioner) if I get married?

A US citizen son over the age of 21 can sponsor his father for a green card. Your marriage to your wife would affect the application in so far as your affidavit of support would include more household members, thus requiring more taxable income to satisfy the minimum income threshold. You should have a consultation by phone with an attorney to explore the facts of your case before taking legal action.