There is a hyperbole which says always a best husband/wife belongs to somebody who really doesn't deserve him/her! For instance, a quite gorgeous girl with a high educational degree and good family, reasonable job position etc. who has an absolutely average-looking husband who has no property or asset, nothing special in his life, no good job, not a justifiable university degree etc. (The same goes with a husband.) I wonder if there is any common English proverb / idiom / phrase that can encompass and explain the above fact/belief?
None that are gender specific. "She's too good for him" is possible, but then so is "He's too good for her".
There are related expressions, for example:
(cast) pearls before swine
Generally this is used when you present something valuable to someone who does not (or can not) recognize its worth, but it can be used in this situation to imply that the man does not appreciate the value of his partner.
Of course, that doesn't mean you can't write a song about this kind of situation, or create a metaphor.
She's Dom Perignon and he's Schlitz Malt Liquor. I don't know what she sees in him.
(Edit) The metaphor doesn't have to be alcohol-related, it could be anything where one side is if high quality and the other of low quality, e.g.
She's a ten-carat sapphire and he's just a shard from a broken beer bottle
She's a purebred Russian wolfhound and he's a street mutt with the mange
She is out of my league. :)– AIQAug 10, 2019 at 22:29
@AIQ That's kind of a different situation. You use that when you like someone who you feel is "too good for you", but you won't ask them out because you think there's no chance. Aug 10, 2019 at 23:45
Good answer except I am confused by the last bit. Schlitz Malt Liquor. what is this? German whisky or something? and why is the fizzy stuff better than whisky, they are not similar to be directly compared? sorry but this has gone right over my head. Is this an Americanism or German ism?– BradAug 11, 2019 at 0:08
1@A-friend "iucky bugger" is generic. It can apply to almost any situation where someone gets good fortune. Also it's almost exclusively British. The American equivalent is you lucky son of a bitch Aug 13, 2019 at 15:23
1@A-friend Same thing -- it's generic, but in a positive way. It indicates envy or jealousy. "Winner takes all" is something else. It refers to the idea that in most competitions, there is only one winner. Everyone else loses. It only applies to romance if two or more people are competing for the same romantic partner. Aug 13, 2019 at 20:34