This illustrates the importance of considering carefully what it is you want before implementing it for a large collection. If you can be clear about what you want, there's usually a way to do it in MC. I don't know what your preferences might be, so consider this just an illustration of the potential...
You like all the music in your collection, so you don't really need a 5-point rating scale. There are tracks you appreciate somewhat more and somewhat less than average, but, beyond that, any distinction is rather fuzzy. So you're happy to use a 3-point scale: 2-3-4. That leaves 1 and 5 for other meanings. As suggested, 1 might be for tracks that only exist in your collection because they're part of an album you like. (Tip: Use [Rating]=[1] as an
Access Control rule to hide those.) As you suggested, 5 might be reserved for tracks you really really like.
So that's a simple, easy-to-maintain rating system for you, but what about your lady? You need to find some way to demonstrate your respect for her preferences, but attempting to do so in the same manner will likely backfire. But maybe you do well know where her preferences differ from yours—in terms of artist, style or genre. So record
that difference as an artist- or album-related value (i.e., [WAF]= -1, 0, or 1). Then create a expression field (5-star format) that calculates her adjusted rating (i.e., [Rating] + [WAF]). Assuming she agrees more or less with your relative assessment in the context of any one album or artist, this should provide her with a meaningful 5-point rating.
This has the splendid advantage of rating her preferences higher than yours, yet Play Doctor would continue to use your [Rating]. You get to listen to what you like, while blaming Play Doctor if she's unhappy. Now if we could only figure out a way to toggle [WAF] with a remote, we could even compensate for mood swings...