I have the same experience of picking up on something feeling “off.” It is definitely difficult to accept being told that everything is fine when you have such an overwhelming sense that something is bothering someone! Sometimes these instincts prove correct (later the person will admit they were feeling x and just didn’t want to talk about it), and sometimes nothing comes of it. I don’t have an answer as to whether these feelings are always correct, but I wanted to let you know that I feel them too. Also of note—I used to feel this way very frequently in my previous two serious relationships (which both ended badly as we weren’t compatible/capable of making each other happy)—I get this feeling WAY less often in my current relationship, even though we’ve been together longer. Dunno if it means anything, but there ya go.