Is it possible to feel if my crush had sex with somebody else?

There is this new co-worker who started flirting with my crush (a female co-worker). I flirt with her and talked to her about my feelings some months ago, but she never gave me a clue if she likes me back or not. She just told things like "let things be and things can possibly happen or not happen", etc. And yesterday, at a job reunion in a bar, this guy flirted her in my presence. I did, too, but at a point I had to leave for an urgency. Today, everything is uncertain. I have no clue how that ended, but I have a feeling that they two might have ended at his home having sex. I have no proof about that. Is that feeling real or is just a result of jealousy from my part?

Is it possible to feel if my crush had sex with somebody else?
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