After getting hit with Truth Serum, Mr. Cat never mentions his crush on Kaeloo, but he talks a lot about his family and backstory. Why? He openly admits to having a crush on her even without the serum, but prefers to keep details about his family and life before Smileyland a secret.
Later on in the series, we find out that Mr. Cat is actually considered to be incredibly handsome in-universe. In other words, Mr. Cat isn't even ugly - he hates his body because he holds himself to beauty standards that are nearly impossible to attain.
