IMHO one can stand so many romantic Movies only when the Love Bug has Stuck him/her. Personal experience here !!
Most of the good Romantic Movies have already been listed here , apart from that you can try the following :
NOTE : These are not total romantic movies as in many of them are multi genre films but they are all good and worth a watch IMO.
50 First Dates : A Romantic comedy , a very sweet movie.
Punch Drunk Love : Another Sandler flick , only more sensible and better this time.
Mein Meri Biwi Aur Woh : Ahww ... u will love this.
Ghost : Dont watch it for its supernatural element but watch it for the chemistry between the lovers. I Liked it.
Mr & Mrs iyer : Another Classic bollywood movie.
Walk the Line : I simply Loved this movie , Joaquin Phoenix is bloody awesome.
Stranger Than Fiction : I Liked this movie as well , a sweet film.
The Illusionist : Ofcourse how can i forget this one , my all time favourite movie.
The Break-Up : I Really enjoyed this movie. It was loud but fun.
Laws of Attraction : Pick this one up only if you r a brosnan fan.
The Fountain : Complex movie but really well made and acted.
Love Actually : This may have already been mentioned but this is likethe greatest romantic flick ever made.
Braveheart : Last but not the least "The Braveheart" , yes its an action film but its equally romantic. A must watch for everyone irrespective of the genre.