Just because you can provide some flimsy after-the-fact-rationalizations* doesn't mean that it's reasonable.
That's ok though, desires/hobbies/cultural practices/etc are generally not based in reason.
/* For example, it's very doubtful that today you would gain any real insight into a persons ability to "provide" from them giving you a diamond...in fact it's more likely to deceive you (they could purchase on credit, buy a stolen/fake one, etc). You'd learn much more about that from simply dating/courting them - knowing about their spending/saving habits, profession, etc.
That's ok though, desires/hobbies/cultural practices/etc are generally not based in reason.
/* For example, it's very doubtful that today you would gain any real insight into a persons ability to "provide" from them giving you a diamond...in fact it's more likely to deceive you (they could purchase on credit, buy a stolen/fake one, etc). You'd learn much more about that from simply dating/courting them - knowing about their spending/saving habits, profession, etc.