What you are describing is less a throuple and more just bog standard Ethical Non-Monogamy with shades of Polygamy. It would be your wife with multiple partners and you making the proverbial (sometimes literal) sandwich.

I emphasize that because there is a lot of media and societal pressure on all sides. ENM has increasingly become divided on gender lines with (cishet) men having been taught by the tates and the manosphere that it is taking THEIR women away from them and ruining THEIR women forever and so far. Whereas women (and the lgbtq community) have almost flocked to it in a similar manner to “free love” back in the day as there is an increasing push to not actually have kids… at which point monogamous sex starts to make a lot less sense.

Whereas throuples are often romanticized. In large part because people watched/read the trainwreck that was Twilight and all came to the realization that “she got two hands…”.

At the end of the day? Every person and every relationship is different and it is really on you, your partner, and your friend to decide what works for you.

For what its worth? Some very good friends of mine are in an ENM relationship and I’ve had a relationship in the past where we also weren’t exclusive sexually. But the ground rule we, and they, use is that they have one emotional partner. Sex is fun and harmless (if you use protection). I broke up with my ex but for completely unrelated reasons and said friends are perfectly happy as far as I can tell. Emotional bonds are where things get REALLY messy. I’ve always avoided it but every couple I’ve known that tried it fell apart within a year or two. Whether that is good or bad really depends on your life experiences and where you draw the line on “save the relationship” and “live your lives”.

So, personally? If you and your partner want to try this I would suggest NOT banging the dude you clearly both already have emotional connections with. But, again, you do you.