Their love for each other when they were young caused them to be entangled throughout their lives. Their love is always like fire in winter and winter in summer.
He and she met and fell in love when they were young; they grew up together and supported each other.
When they were young, they made a wish to grow old together; when they grew up, they made a wish to each other to be safe and happy;
They are both people who keep looking forward, but they always look back when they encounter each other.
They often fall in love at the wrong frequency. Their whole lives are about falling in love at the wrong frequency.
I think the ending is not a be in the traditional sense, but a different kind of he.