List ten words you want in the poem. If these involve rhyming pairs, so much the better. Write them out with whatever comes to mind between them, then refine this.
Think about your beloved. Simply state the wonderful attributes he or she possesses. True sentiment in written form is always its own poetry from one heart to another.
Writing a short love poem is the simplest thing in the world. Well, maybe not the simplest thing, because it takes trust. Believe in what you're writing.