I have heard the same story over and over again.  As couples head out on a bike ride (on single bikes) at some point the guys tend to ride hard and take off leaving their gals behind.  The response is usually something like:  "I feel like I'm on a bike ride all by myself."  It is really hard on both riders.  The faster rider can't ride their hardest because they need to hang back with their partner.  The slower rider gets discouraged because they get left in the dust.  On a tandem the two obviously must stay with each other, and their power and speed are averaged together.

The two of us love spending time with each other.  For us, riding bikes is one more opportunity for us to be together.  On single bikes, even if the two of you ride at the same pace, because of road conditions and congestion on bike trials, you must spend much of the time following one another.  That makes it very hard to carry on a conversation.   On our tandem, we can visit the entire time.  Really the only two times we can't talk are if we're riding on a busy road (because of traffic noise) or climbing a steep hill (because we're winded)!

We have discovered that we can ride faster on a tandem than on singles.  On a tandem you have the rolling resistance and wind resistance of one bike, but you have two "motors."  There is another advantage, and that is in the level of encouragement.  When you are working together, such as heading up a hill, you are continually encouraging each other:  "almost there, we can do it!" 

One other thing we have noticed is that we can start quicker on a tandem than on a single.  As you are waiting for a traffic light to change on a single, you are standing on one foot and balancing the bike while waiting for the green light.  When the light does change, your first few strokes will not be at full power as you gain your balance and get your feet firmly situated on the pedals.  On a tandem this is true for the "captain" (front rider), but the "stoker" (back rider) has their feet on the pedals the whole time, so as soon as the light changes they can pedal at 100% max power right off the line.

There is the matter of cooperation, communication, and working together that you need to get used to on a tandem.  We cover more of that on our learning curve page.

Our conclusion:  our primary reason for bike riding is to enjoy a hobby together.  There is no question that we are more "together" on a tandem, both physically and emotionally.  For us the decision was obvious!