In this world we reside, what we acquire depends on what we can acquire. In other words, if we have the money to, we can buy a house; if we have the necessary educational qualifications to, we can get a high-paying profession. I guess the idiom/phrase I'm trying to look for deals more with romantic relationship partners.
From what I have observed, it's common that people choose their partners in relationship based on their own quality, by this I mean for example, someone who's wealthy tends to prefer a partner who's also wealthy as well. Someone who's very good-looking tends to have higher standards and aim for a partner who's also good-looking as well although there are exceptions but that's generally the case from what I've observed. Unattractive individuals are more likely to have lower standards appearance-wise and favour relationship partners who are similar and not quite that good-looking, for reasons either maybe because they feel insecure that their partner might cheat on them or that they feel they're not worthy of them.
So is there an idiom/phrase that describes this idea, that describes something along the lines of:
(it is meant to be that) what you get depends on your own quality nothing more and nothing less, (if you attempt to be with someone who's way above your standards the relationship will ultimately fail).