“Love you too” is correct and “Love you to” is incorrect. “Too” means the same thing as “also” while “to” is a preposition and part of an infinitive verb in English.
I love you.
I love you too.
We need to use “too” because we want to reciprocate and say the same thing back to someone who says “I love you.
Too vs To
To is a preposition and part of the infinitive of a verb.
I am driving to the bank.
I need to eat right now.
Too is an adverb that means “also” and “excessively”.
I miss you too.
I ate too much ice cream.
I love you too or Love you too
Sometimes people drop the subject “I” when saying” I love you too” because it is obvious and implied that subject is “I”.
I too love you or I love you too
“I too love you” has a different meaning to “I love you too”.
“I too love you” means that I in addition to another person love you.
Let’s look at an example:
Peter: I love you, Tina
John: I too love you, Tina.
Tina: And I love you both!
So be careful not to say “I too love you” when you really want to say “I love you too”.