SilentCom said:
Since when does EVERYBODY hate their ex? I think this sort of thing is completely situational, depending on the context of the breakup. Sometimes it's a simple "I don't think we're right for each other" thing and things aren't too bad. Other times somebody cheats, or lies, or they have a big fight, or somebody has a total meltdown because they don't handle rejection well. Those breakups have more raw emotions attached to them, and that can easily turn to resentment.
And I think the reason you've come to assume that EVERYBODY hates their ex is because most breakups are messy. And you are also assuming that all relationships run on the purest love. That is also false. There are a million different reasons people get into relationships, and love is not always the top contender. To answer your question, yes, love is a lie in MANY cases. Also, it is possible to both fall in and out of love. Just because you love someone at one time doesn't mean you will always love them.