While some writers listen to soft romantic music playing in the background for inspiration while writing romantic dialogue, I prefer listening to the lyrics of love songs from the 1940s.
The words--especially those of Oscar Hammerstein ("Some Enchanted Evening") and Irving Berlin ("Always")--carry me to a special mental place where I translate their beautiful thoughts into beautiful words for my stories.
Try inserting well-known lyrics into your romantic dialogue. Then, when you've completed the scene, go back in and substitute the songwriters' lyrics with words of your own. Paraphrase!
Almost immediately, you'll see how the poetic lyrics from those 1940 love songs have influenced and improved your word choices. Try it. Your romantic dialogue will sing off the pages.