Tl;dr: my partner of 5 years and I are newly open in our relationship, and are very interested in something casual with our friends who are also in an open marriage. I'm looking for advice around that specifically, but general advice is welcome as well.

Hello, all. My fiance(23f) and I(24m) opened our 5 year old- relationship up a few weeks ago. We have been keeping communication lines completely transparent and constantly discussing boundaries. In doing so, we found out that we both are crushing on 2 of our friends(late 20s m & f) who happen to be in an open marriage.

We've spent the last ~year getting pretty close to them on a platonic level, the 4 of us hanging out almost every week. My fiance and I are both bi, I tend to lean towards men. The couple we're interested in also happen to be bi as well. They've never shown any interest in us, beyond a few infrequent jokes. That could be disinterest or just respecting a formally monogamous relationship.

As I stated, my partner and I would like to pursue something intimate with them, but we're both very new to these waters and are not sure how to go about it and what to expect. My best friend hangs with us every now and then, and I had her conveniently ask about our newly open relationship in front of the husband. He didn't comment at all directly to it, and didn't rejoin the conversation till we had sorta changed subjects. (Trying not to overthink about that)

I guess we're wondering how to go about it. We genuinely value their friendship, so we're afraid of ruining that. But at the same time, the mutual benefits seem worth the small risk. Also, we're very attracted to them. Any advice regarding this is appreciated, and general advice around polyamory is also welcome.

Addendum: posted originally in /polyamory and was quickly made aware my partner and I aren't actually polyamorous, so I'm trying here. My stance on this topic has also changed from excited to cautious.