How do I make wife that I want to get cuckold?

OK, here is a few tips. Start watching mmf porn, then go buy a nice size dildo and other toys. Use the toys in bed on her, without you doing things and show her that you like this! She must see that you like her beng satisfied without you. Then, obviously, talk to her. Openly talk to her and ask her. If she says OK, then  fine. If not, then you shall not insist. Its her decision at the end of the day