It's an unforgettable film. Not trying to be anything more than it was--romantic comedy/drama---it was brilliantly realized. The part was written for Cary Grant, or seemed to be, and Deborah Kerr could play any role and be excellent.
The so-called chemistry of the romantic interest was as good as it gets. The production was done expertly, from the script to the sets, etc. We have to make exceptions for how 1950's Directors of Photography lighted everything, giving the interiors a bright, brittle look. They learned from European Directors eventually.
In my opinion, "Affair" was one the best productions, all round, of the 1950's. Tom (I always cry at the end).