Three's Company

They're a married couple in their early thirties. Both are career driven people and before April this year, I was fucking them both without the other knowing.
Amy is someone I met through a mutual friend at work. She basically discovered I have a large penis and wanted to relieve a lonely weekend with her husband away on a stag weekend.
She arrived at my place around seven o'clock on the Saturday night, and we were having our fifth fuck as the sun rose on the Sunday morning.
What Amy, or I for that matter didn't know, was on the Friday lunch time at a gay cruising place I know, I fucked her husband Michael as he leaned against a tree. He'd sucked me hard first, then donning a condom, I screwed the arse off of him. Making him cum without him touching his cock.
It wasn't our first fuck by any means, as I'd fucked Michael a few times at the cruising place, but more so actually in his home.
And it was in their home fucking him in their shower, that Amy caught us.
There was some initial "What the fuck" comments. But once Amy recognised me and I her, the penny kind of dropped for Michael.
Even so, without having cum I might add, I left them to discuss their marriage and from what I now know, they discussed me too.
Their decision was.
The following evening on their marital bed, I had a threesome, fucking them both. And it was especially horny watching Amy's face as my cock slid up her husband's arsehole. It was obvious it was turning her on. And it was also obvious from the way Michael moaned with delight, he was more than comfortable with his wife watching him. At one point as they kissed passionately kneeling next to each other, I switched from fucking Amy's arse to fucking Michael's and then back again.
At the end of the evening they were having a sixty nine with Michael underneath his wife, licking and sucking her clit, as I fucked Amy's rear hole. When I came up Amy's tight arsehole, Michael quickly moved them so he could devour his wifes rear, licking and sucking my cum from his wifes creamy bottom.
From April to now I've continued to fuck them both, but we sometimes now have occasions when one of them cannot join in and has to watch only.
Usually the following day, the one who I've not had sex with will visit my home and we'll have a real dirty session fucking.
As far as I know, I'm their first extra marital partner and they seem to really enjoy their weekly fucks with me. I'm certainly enjoying fucking them, that's for sure.