Why do toddlers say "Mom, I do not love you"?
My opinion that toddlers know how strong those words are.They are using these words to try and get what they want. Some little kids say things they don't really mean deep down inside. Take it from someone living with a four-year-old. Small children have very basic emotions, so instead of saying "Mom, I don't like that you punish me/deny me something I want", he/she says "Mom, I don't love you".
First of all, they're probably trying to get a reaction, so don't give them
one. Secondly, tell them that you don't like them saying that and suggest a
more appropriate phrase to let them vent their displeasure.