The passionate love scene is a classic and usually key to the story and development of the characters. Often it is the climax, excuse the pun, to a building of emotions and scene setting. Despite its importance it is often and easily done badly.
There are various reasons why as scene can be done badly. Sometimes the very importance of a scene can make it difficult to write because we put pressure on ourselves to get it right. What makes a love scene more difficult is the inhibition needed for such writing.
As people we naturally find sex, nudity and passion somewhat embarrassing and as long as we feel that way we will let our own embarrassment hinder how we write.
The whole idea of this time of scene is the freedom the characters have, how they give into their desires and open themselves up. As a writer, in order to do this successfully you have to be able to put yourself in the same mood and forget embarrassment. Hopefully the right type of music to get you in the appropriate frame of mind is a good start.
'Your Hands Are Cold' from the movie Pride and Prejudice starring Keira Knightly is a good start and should get your heart pumping.
'Bad Things' by Jace Everett and made famous by the True Blood series has catchy erotic lyrics. 'Wicked Game' by Chris Isaak is a haunting classic.
'With or Without You' by U2 is another classic powerful song.
For more of a romantic love scene try 'Colourblind' by Counting Crows or
The Fray's 'Look After You' .
The key thing is to be in the right mindset in order to right the scene and not to sensor it or tone it down either. That can be done later in editing. Feel passionate about the scene and put it all down in the first draft.