His age, or rather your age difference will be the least of your problems. To be brutally honest, there are no advantages to loving a married man unless you plan on existing on fantasy alone. He's married, happily or otherwise, he's taken. The disadvantages are too many to mention or count - heartbreak and disappointment for you, honesty and loyalty issues for him, just to name a few. I know you can't help who you fall in love with, but you can help what you do about it and what you should do about it is move on. Sorry, brutally honest, like I said.

Best wishes,
-J.