In case you hadn't already heard, people can't be fixed by other people. That stuff comes from within. We are who we are, we rarely change, and chances are, that damaged person you fell for is just fine for someone else.
Making people into projects leaves them resentful for not being accepted "as is." And really, that's not bad logic.
Not all of us are lucky enough to fall madly in love with someone in high school, grow up to marry them, and live happily ever after.
Fortunately, recognizing the relationship learning curve is exactly how we (eventually, maybe, someday) end up with the right person. All that heartbreak we suffer early on prepares us to be better partners to people better suited for us.