It's not trite, it's just missing part of the equation. The key is not whether someone is extraordinarily self-reliant and mature. The key is how much they are still going to grow. In an intimate relationship, it is more risky if one partner had done a significant part of their cogitating on life, and the other is just ramping up. If the relationship is founded knowing one person is likely to change a lot, that is one thing, but if you fall in love with someone and think that because they are mature they aren't going to change significantly, well, that's a recipe for heartbreak.

Consider the case of a mastiff puppy that falls in love with a corgie dog. No matter how much the mastiff might *wish* to stay at the same level as their beloved, they're going to grow. A lot. And their perspective will change. A lot. No help for it. They might still love the corgie, but the corgie might not be able to take the heartache of never being able to keep up.