Who is this John Legend and why is he singing about my relationship?

[Modem Butterfly]

Will and I have had arguments that could peel the paint from the walls. We're both yellers, unfortunately, and while we agree on all the big issues (family, religion, fidelity, money, etc.) when we argue it's about the most picayune, miniscule shit imagineable (once we had an argument over whether or not rap music is derivative or a new art form; neither of us even listense to rap). After 10 years, we're more in love with each other than ever. But when we heard this song yesterday, we both agreed it cut really deep:

Ordinary People - John Legend

Girl I'm in love with you
This ain't the honeymoon
Past the infatuation stage
Right in the thick of love
At times we get sick of love
It seems like we argue every day

I know I've misbehaved and you've made your mistakes
And we both still have room left to grow
And though love sometimes hurts
I still put you first
And we'll make this thing work
But I think we should take it slow

We're just ordinary people
We don't know which way to go
Cause we're ordinary people
Maybe we should take it slow

Take it slow
This time we'll take it slow
Take it slow
This time we'll take it slow

This ain't a movie, no
No fairy tale conclusion y'all
It gets more confusing every day
Sometimes it's heaven-sent
Then we head back to hell again
We kiss and we make up on the way

I hang up, you call
We rise and we fall
And we feel like just walking away
As our love advances
We take second chances
Though it's not a fantasy
I still want you to stay

We're just ordinary people
We don't know which way to go
Cause we're ordinary people
Maybe we should take it slow

Take it slow
This time we'll take it slow
Take it slow
This time we'll take it slow

Maybe we'll live and learn
Maybe we'll crash and burn
Maybe you'll stay, maybe you'll leave, maybe you'll return
Maybe you'll never find, maybe we won't survive
Maybe we'll grow, we never know
Baby you and I

We're just ordinary people
We don't know which way to go
Cause we're ordinary people
Maybe we should take it slow