When someone says "I'm sorry you should feel that way", they're using should in a different way than someone who says "you should ditch that no-good, lazy boyfriend of yours". The latter use is called the mandative should, expressing as it does a command or recommendation. The first also has a name; it's called the putative should.
Putative means supposed or presumed, and the putative mood, used when the speaker doesn't have direct evidence of something but is inferring it, is common to a number of languages.
The putative mood is, relatively speaking, a bit player in the English language. The two heavy hitters are the indicative mood, used to make factual statements or pose questions ("You are upset", "Are you upset?"); and the imperative mood, which expresses a request or command ("Get your butt over here.")
A little further back comes the subjunctive mood, which shows a wish, or doubt, or something that is not established fact ("If I were you, I'd be upset too"). The subjunctive may be disappearing from English, and many writers - and even more speakers - no longer feel bound by it. "If I was you" is perfectly acceptable in many quarters these days.
By comparison with all these moods, the putative feels quaint and antiquated - like something you might hear in Downton Abbey. It's disappearing by, literally, disappearing. Whereas "if I were you" is being replaced by "if I was you", "I'm sorry you should feel that way" is being replaced by "I'm sorry you [no word here] feel that way". One reason, perhaps, why grammar pedants often rail against failure to observe the subjunctive, but rarely against failure to observe the putative. It's harder to notice something that's no longer there than it is to notice something that's been replaced by an alternative.