We'll see what happens. Yes, but ... OK, I will try.
There are so many ways to say No. Some of you might've realized that's what gets said. But I've seen very few who understand why it gets said in circuitous soft words, other than attributing it to race or upbringing.
Because of what happens when you say No. There's always someone else who's waiting to say Yes. Time after time, each No you say shrinks the number of times you get asked and life's opportunities show up as questions. The fewer times you're approached with a question, the fewer times will you get to say Yes!. Each No shrinks the funnel through which other people interact with you.
Being reasonable produces the opposite result you want. Those that say "Yes, let's do this!" and flake out are often asked more often than those who can offer a negative in time. In fact that those who say "No, I'm meeting a friend tomorrow" only to have their friend flake out is worse off than someone with double bookings.
Whether the opportunities are social, personal or professional, those that a "Yes, we can try" are preferred to the respectful No. Of course, we prefer the "Can Do" people here.
The definite negative implies intention, while the loosely held hope is always treated better. The negative is interpreted as sub-textual while the other is taken as a circumstantial "stuff happens" even when the eventual end result is the same - probably worse for the "maybe" because it steals away the ability to plan an alternative.
In such an environment where all Yes-es are Maybe, being "Definitely Maybe" is understood well - and saying "No" becomes a "No-No".
In short, when it comes to saying No - I'll try.
--The right word may be effective, but no word was ever as effective as a rightly timed pause.
-- Mark Twain