My wife and I have always done things together. I was a runner through my early 40's; refereed field hockey at all my wife's tournaments. During that same period we bicycled with our kids. We moved and got into doing things with horses. Years later, in our early 60's, we had stopped showing horses and started up with cycling on singles, but we really couldn't ride together. We saw others on tandems and thought we would investigate. Now we ride 3+ times a week and do as many 100K organized rides as we can. Yes, there are grumbly times: we're climbing, it's warm, we've already ridden 50 miles, but it's 98% good
As captain I've found there are two danger zones: thinking about how much easier a tough climb would be on a single and picking rides that may be too difficult; avoid these and life is good on a tandem. Of course, a young(er), strong(er) team has a different perspective.