I'm a jealous girlfriend?

Ma

So my boyfriend recently told me that one month ago, one of his female coworkers was speaking badly about me and claiming that I was pouting and appeared "jealous" when he and I ran into her one day and he said hi to her real quick. He says he was surprised by her claims since it is unlike me to behave that way when he speaks to other girls. He was so upset about her saying these things about me that he blocked her on social media. I don't remember this happening at all since it was two months ago, and I can't even recall of a time where he said hi to a girl and I felt jealous. I don't even remember seeing this girl!! I have never felt any jealousy towards any girls around him, and have even tried to become friends with them at times. My boyfriend was sure that she was lying about me pouting, and I'm pretty sure she was lying as well since I don't remember this ever happening. WHY would another girl make up this kind of stuff about a guys' girlfriend though???? I've never met this girl before so I don't know what she even looks like lol.