Some quick motion sketches.
I was doodling hearts in Adobe Illustrator.
The double heart is mine. The font is Action Man, which isn’t mine.
Another good variation would be to use the word “forever”, with the “o” being the double heart.
I made some Zazzle things with this design. Those can be found here.
I made this for a greeting card. I have several versions up on my Zazzle store. Here’s one: http://www.zazzle.com/greeting_card_note_card-137648537833700527