Tell your significant other that you like his/her “odour” and see how he/she reacts! Chances are the person will never speak to you again. The word “odour” has a negative connotation; it means foul smell. An odour can never smell good; it’s always bad.
*The odour of rotting fish almost made me vomit. *The odour from his dirty socks was disgusting.
A smell, on the other hand, can be either good or bad. You can talk about the smell of rotten eggs and the smell of perfume.