In proving foresight may be vain:
The best laid schemes of mice and men
Go often askew,
And leaves us nothing, but grief and pain,
For promised joy!"
Lennie and George are not alone. They are with every other man in their world who has a plan. Unfortunately, like the poem says, "The best schemes of mice and men go often askew." George and Lennie had a plan, but any plan can go wrong and that is what happened to theirs, which left them with nothing but grief and pain.
So even though the title, "Something That Happened" is perfect for this story, its actual title, "Of Mice and Men" is more appropriate. This title, which comes from Robert Burns' poem, relates mores to what happens in this book. Steinbeck chose a great title for his book and there is not a better one.