In the original, Celia Johnson played the mousey, lonesome little housewife very well, thus making her believable when she fell for the charming Trevor Howard. In this remake, Sophia Loren is hardly mousey and desperate. She plays herself, strong, one-dimensional, knowingly drop-dead gorgeous, fashionably dressed, walking with the self-assurance and feline power of a runway model. Very hard to believe she'd have settled for her boring barrister husband (who never seems to be at work but puttering around the house or playing games with the kids all the time) or want a skid row casework job. As for the "brief encounter" with blazing blue-eyed Burton, I could not see "love" between them. Burton did a decent job of faking it; but Loren makes no such effort, bemused perhaps but basically playing up to the cameras.
In the original film, one could feel love and passion between the two star-crossed protagonists, but Celia was too scared and guilty-feeling to commit to marrying her true flame. In this film, Anna (Loren) refuses the doctor because she doesn't really love him (or anyone but herself) and certainly wouldn't want the bother of self-sacrifice or the uncertainty of losing control and changing her queen bee life.