You can pick from Napoleon’s letter to his Josephine or Beethoven writing to his Immortal Beloved –
“…never misjudge the most faithful heart of your beloved, ever thine, ever mine, ever ours…”
Of course, Elizabeth Barrett Browning’s Sonnet 43 is timeless.
“How do I love thee; let me count the ways…”
or John Updike…”We are most alive when we’re in love…”
Too much schmaltz for you? How about Lisa McCourt’s I Love You Stinky Face?
I found a site for free printable Valentine cards –