So... you've got a sweetheart and you want to tell them how special they are and how much you love them... but you're not very eloquent with words? No problem. Here are a few sites that feature Valentine's Day poetry. Some of the poems are free for you to use either personally or commercially. Some are not. Use the free ones as is, or use any of them as inspiration to write your own poem. Just be sure not to violate copyright laws.
If you still can't find "just the right words", just write something from your heart. That's the most special message of all.