You feel guilty without having done anything
After every conversation you feel you've let them down, though you can't say how.
Rule out first
You may have done something you've forgotten. They may have a real grievance they haven't voiced. Your own mood.
What could explain it
Harsh superego (inner critic): You feel this with many people; the guilt is your inner critic, and they only set it off.
Emotional blackmail (fear, obligation, guilt): The guilt arrives with a request; it goes away when you comply and comes back when you refuse.
Masochistic (self-defeating) character: They suffer visibly and turn down your help, so you feel responsible and useless at once.
Projective identification: They seem untroubled by things they've done, and you feel the guilt they aren't feeling.
Passive aggression: Sighs, hurt looks and pointed silences carry anger; you feel it as guilt because nothing has been said.
Doer and done to (Benjamin): The guilt comes inside a conflict where each of you feels the other is doing it, and you've accepted the doer role. It lifts when either of you names one concrete thing you did.
A next move
Ask them directly whether something's wrong. A clear grievance means something real to repair; 'nothing' with continued hurt means passive aggression; a demand means blackmail.
If it’s you
Is this guilt mine, or did I pick it up from them?