Best Answer - Chosen by Voting
愛してる(ai shiteru.)
We tend to omit the subject in speaking.
Usually people don't say "私はあなたを愛してます," which is a direct translation of I love you since this sounds too grammatical or mechanical for native Japanese people.
you can also say, 愛してるよ(ai shiteruyo.)
This sounds more conversational.
A Japanese phrase ends with よ(yo) would give more impression of telling or talking to the listeners than without saying it.
