They most likely didn't feel a connection when you kissed. I've dated someone, saw them a few times , liked how they were as a person and then when things got physical, I lost interest. It was awkward and just didn't feel natural.
I have also dated someone who I did not find attractive at first, got to know them and developed feelings that way and when things got physical, there was attraction.
Sometimes for some people, it comes down to the physical chemistry.