His partner isn't simply what she seems: he sees her through a mesh of memories. She isn't just the woman she is now, but a compendium of all she's been.
She's still that girl in light-blue jeans (stunning, with her tan and long, dark hair) who made his life seem suddenly worthwhile, when they were students, crammed with dreams.
She's the mother of their children, too, and though they're starting to leave home, he remembers all the care she gave: help with homework, food and clothes.
Or she's a forty-something lady on a beach, who seems untroubled by the sun's harsh rays - soaking up its warmth for hours on end, while he must leave, in search of shade.
She could be likened to a Russian doll concealing all those other selves inside. When one has known and loved someone so long, there's much, much more to them than meets the eye.