The only answer to this was: Yes. No. Maybe.
If your novel is entirely about these two characters getting together and they don't, then the reader will be disappointed. I read a novel a few years back where the main character doesn't realise X is the man for her until near the end (despite lots of Unresolved Sexual Tension simmering between them), then finally at the end of Chapter 23 decides to tell him how she feels. I eagerly turned the page to Chapter 24 and read: The following year... What had happened in that following year was quickly summarised, and the book ended with every one happy except me, the reader. There had been all that emotional build up, and for nothing. The author had cheated me of the scene when the two characters got together.
On the other hand, if we'd had the scene and it had all gone wrong, X had revealed that he'd been interested but had got fed up with waiting and was now involved with Y I'd have been - not exactly happy (because I'm a sucker for a happy ending), but satisfied as a reader. In Adaptation Charlie Kauffman does much the same, and it sits naturally with the main character's story line. Joanna Trollope did something similar in The Men and the Girls and not only was it satisfying, it worked better than the more traditional ending.
So, in answer to the question, it's not compulsory to fulfill reader expectations; in fact, it can work just as well if we subvert their expectations and give them something different. What is compulsory is that we write the scene. It's not okay to cop out and write: The following year...
