Short answer....a lot.
About 4 years ago we got into mfm fun with a guy we know, we've done it many times with him. We're all comfy together now and it's a fun, sexy, relaxing night for all of us. This has opened our thoughts about sex fun like you can't belive. Wife and I have sex way more often than we used to. She's super horny for days after he's been with us.
Yes I beat off thinking about our fun often. But I also fuck my wife often.