This is a bit of a brag and a bit of an ask for advice. So I (M36) have been with my wife (F33) for 11 years. She was my first experience which I really don’t mind and I am happy with it staying that way. I was a late bloomer but happy.

My wife had multiple experiences with other people before me and I have never held this against her realising I was the less conventional one.

Now she has a sister also 36 and she is quite close too. SIL is quiet, shy and as far as we are aware has never been romantically involved with anyone.

I understand the difficulties that being a virgin later in life can have on self esteem and how as time goes on it gets to be a bigger and bigger thing. My wife knows she is definitely a virgin and definitely heterosexual.

We have never considered an open relationship and never really considered any type of threesome scenario etc. My wife had expressed before now that she feels sorry that I didn’t get to experience more. I am happy and content but I would be lying if I said I didn’t have urges. We are a happy couple and happy to talk about celebrity crushes etc.

My SILs situation has been growing in my wife’s mind recently and previous to COVID my wife was taking her out to try and help her to making the first steps.

SIL wants kids but like I said her concerns for time etc are growing. So my wife has now brought up to me that maybe I should “date” her sister and be her first sexual experience. The thinking is that I am a man she already trusts, I know what I am doing and I will treat her with respect and allow her the space to gain the confidence with men she lacks. The bonus for me is that I get to try something different. Her sister is quite different from her different hair colour, slim athletic figure with a flat chest. I see these differences as a bonus as my wife is my ‘type’ but change can be fun too. The SIL is also into yoga and super flexible!

We are confident our marriage can take this new angle and I have suggested that if my wife wants to “try something different” as well. I will be fully supportive. Practicality wise we are planning a chat group between the three of us so all communications also involve my wife. Nothing would happen in our family home but at the SILs place. I would turn up, spend some time with her like a date and progress to the bedroom. There would be no possibility of a three in the bed scenario. My wife isn’t curious/incestious at all and isn’t sure of the three of us being naked together.

The questions are how do we bring this possibility up to the SIL and are there any other pitfalls to this?

Sorry for the long explanation and this is a throw away as you would expect.

PS there has been mild flirtations between me and SIL before but all above board!