In matters of the heart (or financial portfolio) nothing is guaranteed, Madam. Yes, he lead you on, but he ‘owes you’ nothing.
At any time, you could have set an ultimatum. He probably thought you were playing the waiting game too. Maybe you were fine staying with a man you knew to be unavailable on your terms.
Who knows what he said in private?
He could have told her he didn’t want marriage.
And even if he promised her up and down, did she not figure things out in year THREE or FOUR or FIVE or SIX or SEVEN????