It's easy not to have an affair: have some will power and just don't. It's like beating up someone who mad you really angry, you don't because it is wrong. Ask the guy to tell his wife about the kiss, making it clear it will go no further, or if he doesn't you should. I have a very tactile relationship with all my friends, we often kiss and cuddle, but with consent of everyone, partners and spouses.
Another idea is looking into Polyamory (www.polyamory.co.za). It is having more than one loving relationship at a time, with full knowledge and consent of all involved.