50-ish couple here, married 25 years. Been into mfm with (same) guy for 4 years off and on. Last 2 years 2 or 3 times a month.
Long story on how it started. 1st time, drinking, hot tub, he fucked her over the back of the living room couch, took maybe 3 minutes utes from kissing to him finishing then he left. Weird, scary as hell, jealousy for me, guilt like cazy for wife. Did it like that 5 or 6 times with the same feelings each time.....but wife was on fire horny for me after. Got easier each time. Now it's a regular thing for us, it's a fun, relaxing and sexy night for all 3 of us.