Well Ariel is irresponsible, reckless and has proven to put herself in perilous situations. And so King Tritan has every reason to fear for his daughter’s life. There are predators in the ocean like sharks which can eat her. He’s likely aware that Ursula [his sister in the Broadway show] is a huge threat to his family. And if you believe the prequels have any precedence, then he has absolutely no reason to trust humans seeing as they killed his wife. Granted he may be overbearing but Ariel is continuously testing his fears.

So to answer your question “why is King Tritan so strict on Ariel”,
Because he loves her and is afraid of losing her.

Like all good parents, he Loves her and wants to protect her!

I don't want to go into too much detail about the appalling prequel, but King Tritan Loves his family very much, misses his (dead) wife, Ariel is the youngest, the baby of them all, and she resembles her mother so much, he is also scared of losing her, too.

Her mother was killed (accidentally) by humans, whilst they were playing above the surface. So, he is quite right to forbid her to even think about going near the surface! Out of Love and protection. He finds it difficult to express his Love without upsetting Ariel, like many fathers. Believe me, I should know.

16 year olds don't know everything, they demand respect, rather than earning it. It's just a lack of communication. I can only assume that Ariel is pretty much her mother's double, so I'm sure Tritan is familiar with her fascination of the human world.

Without rambling too much, if he wasn't strict, there would be no story (= Disney's Little Mermaid is my favourite version.

Hope that helps!

He is so strict because he loves her and doesn't want anything to happen to her.

She looks like her mom and she's his daughter. Of course he would be strict! Especially since Ariel is headstrong and keeps getting into trouble, it would be difficult NOT being strict.

Because she always do whatever she want,i mean that she never listen her father.

I think he is very protective with her and afraid that she'd get hurt by the humans so as he realises that Ariel is in love with Eric he turns her into a human in the end so that she can be with her one true love

Because as all Dads and Rulers he really just wanted what is best for his youngest daughter. I love my Dad very much, but being a twenty yr old him and I fight alot because we dont see eye to eye. But I know some day I will hug him on my wedding day and say " I love you daddy " just like Ariel did because I knew in the end no matter how much he got mad or yelled at me he really only wanted what was best for me. That is all That Triton wanted for Ariel.

She's the youngest and he doesn't want his baby to grow up too quickly. She's also very rebellious

i think he is so strict because she is his youngest daughter and he loves her and wants to protect her he knows the dangers of the world and really just wants her to be careful but shes young and naive and carefree and stubborn and a little rebellious which makes keeping her safe hard so he gets fustrated but i think he is just rying to do whats best for his daughter because he loves her soo much

Because she reminds him of her mother. She's everything adventurous, and musical and it makes him sad