If you're not happy from the beginning, why are you even in the relationship? And yet you're absolutely right lots of people get into relationships with somebody who doesn't at all represent what they truly want.

As far as I'm concerned, it's not the person they've chosen to be with that needs work, it's themselves!

If you're in the right relationship, you automatically want to be the best version of yourself, and the best version of yourself would likely turn out to be exactly what the person you're with would want you to be and vice versa.