How do you know a guy is bullshitting?

A guy I wasn't serious about just ended it with me and my ego is a little hurt lol. I never initiated texts bc I wanted him to take the lead. I never called either and he said he doesn't like talking on the phone. I had to encourage him to take me out bc he wanted to Netflix and chill and I was against that so I made a suggestion for a restaurant and we had planned a date today. He just texted me saying he met someone else and he likes the connection they've established. I don't believe him, I just think he's a cheap ass but how do you tell someone's lying? I told him I had other plans and to take care. I really do, I have a lot of errands and was going to cancel if I couldn't make it. How do you know the bullshit?
How do you know a guy is bullshitting?
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