Here are the requirements to apply for a 60 day extension of stay to visit your wife.
Your wife will need to be with you.
Copies of your passport photo page, visa or existing extension stamp and arrival stamp. Copy of TM6 departure card.
Copies of marriage certificate, signed copies of wife's house book registry and ID card signed by her.
Some offices may also want a copy of your Kor Ror 2 marriage registry recently updated by getting a printout of it at a Amphoe.