When you're attracted to someone, are they usually attracted to you?

I am a very insecure average looking person who always doubts myself when I feel someone is attracted to me. I ask myself a million questions, trying to prove the guy isn't attracted to me, so I won't be hurt. I used to always be wrong, but given my age, 43, I feel I have better yzitation skills than I used to. I'm totally hot for this guy I work with, like never before, except for my first love. I'm always right about my gut instint when it comes to my friend's love lives. I tend to sabotage things at the initial stages of dating, so I often never get to the stage where I can really tell if the guy is attracted to me. Also, I've never had a guy this into me as this coworker of mine. He subtly flirts with me and we haven't known each other for very long. He is a very nice guy, too but has an ego too cover his insecurities. Does gut instinct usually prove you right or wrong when you think someone is hot for you, when you've never had many people attracted to you before?