Interesting thread.
DH and I dabbled in multiple partners before we got married, in our 20s, but 3 children and 10 years of marriage later, we are fully monogamous.
But I too wonder about the logic of only being sexual with one person for 40+ years. Seems rather limiting to me, with so much variety on offer!
I am also bisexual, so that's something else I would like to explore but currently don't.
We have sort of discussed it, but for the same reasons a lot of people have talked about on here (jealousy, insecurity, wondering about falling in love with someone else), we haven't taken it further.
Part of me thinks wait until the kids are older, as a bit of a safe guard, but then the other half of me thinks I will be less attractive in 10 years' time so now is the time for us to make the jump!
There was a brilliant set of articles in the Sunday Times magazine about 6 weeks ago, which was all about this subject, and more... Couples in c.10 yr marriages looking for more than their current set up, female libido post child birth, open relationships etc... Was very eye opening and DH and I discussed it then, but work and life has gotten in the way again of discussing further!
Will follow this thread with interest.