Nobody's saying rush to marriage, but it doesn't take two years for you and your partner to decide whether you like each other or not. If there's still uncertainty after few months of dating, something ought to be wrong. You don't spend that many weeks, days and hours with a person and not know what you think of them, that simply doesn't happen.
Just imagine someone saying: "We've been dating for six months total but I'm not sure if I like them, I may need six more to get to know them better." How uncommitted do you have to be for this to be the case? That reeks of mutual disinterest, false hope and pretense that somewhere in the future things will work out.