"Okay, we aren't perfect, but everyone knows relationships are like ill-fitting albeit beautiful shoes. You can still walk in them even if they're not a perfect fit.
You run the risk that you'll never grow into them, and there's a chance they'll cripple you for life. Or maybe they're great to dance in, but long walks are out. Or long walks are in, but dancing is out. Or you can go ahead and do everything in them but you'll have big, gaping, bleeding blisters the next day.
Perhaps you'll develop a bunion. And then the pretty shoes will fade and scuff as the years go by, and no matter how hard you polish them you can never restore them to their pristine just-out-of-the-box state. So now, not only do they hurt like hell, but they're starting to fall apart."