Annoyed with myself

Got some stuff going on with my little life lately that makes me both annoyed with myself and annoyed with a couple of other (actually several other) people.  Why do people constantly feel the need to talk to someone who is in a relationship?  Can't they just have conversations that don't include sex or dreams about each other?  Why do they need to throw out little flirtations and crap, feeling the other person out for a sign of reciprocated feelings?  I don't understand this line of rationality at all.  I'm annoyed with myself because I let it get to me when I see it happening, or when I think I see it happening.  Maybe I am too sensitive - well, yeah, I AM too sensitive, but I've gone through it before with my ex-husband, so I'm a little more cautious with my trust these days.  Some things that are said/typed and are perfectly innocent to a normal person send me off in a near panic attack, suddenly not able to breathe, field of vision closing in, chest pounding almost audibly.  I bring it on myself though, because I constantly NEED to know.  Why can't I just stop?  When will I learn that ignorance truly IS bliss and leave things alone?