Really interesting thread.

My OH and I exist in a constant state of cycling harmony.
Initially I was the only one who cycled, but we eventually invested in a pair of hybrids and had many hours of fun trundling along the highways and byways of rural England.
Then one year she had time on her hands and revamped my old steel framed road bike. The nail in the coffin.
I rediscovered the thrill of the road, she felt like she was missing out, invested in a road bike herself, I upgraded to a lighter frame - and that was that.
We've been co-conspirators in our addiction ever since.
She's now stronger than I am, which is good as it keeps me on my toes and ensures I get the miles in, just to keep up.
OH is about to upgrade again to a carbon frame later this year - and hopefully my time will come at some point next year!
Bike shops are lethal as we both have no self-control - and get a thrill from seeing that "biker grin" on the other's face.

It was a significant birthday for me this year - and my treat was a trip to Kent to watch the Tour De France go by. Only cyclists would think that romantic!