How about something that uses the deer/dear pun. Something like "you are the one I hold deer" or "this is for you, because you are the deerest thing in my life".
Otherwise, if you want something more serious and romantic, just check out Tumblr. There are sooooo many blogs with love quotes and stuff like that, but personally I think 'unoriginal' when I see that - so better to write something that means something persnonal to he two of you then copy a random quote from the internet
