I had always taught that Japanese normally say "watashi wa anata o aishitemasu" whenever they want to express love to someone.  But when I learned about Japanese language and culture, I discovered that such is not the case.

The expression "watashi wa anata o aishitemasu", which I first learned from Leah Navarro's song "Isang Mundo, Isang Awit", is indeed a correct translation of the English expression "I love you", but it is rarely used by Japanese.  There are several reasons to this and I will try to discuss them below.

But before I do that, let me first explain the words used in the expression. Watashi, marked by the topic marker wa, is equivalent to the English word "I".  Anata, followed by the direct object marker o, is the translation of the English word "you".  Finally, aishitemasu corresponds to the English verb "love".

Omission of the first-person pronoun

When the topic of the sentence is the subject of the verb and if that subject is the speaker, it is usually omitted.  So if you want to say "I will eat apple", you will use the verb tabemasu (Japanese of "to eat") and you will normally say "apple o tabemasu" instead of saying "Watashi wa apple o tabemasu".  This partly explains why "watashi wa anata o aishitemasu" sounds unnatural.

Avoiding the second-person pronoun

The word anata, meaning "you", is not used much when speaking to someone directly. There are situations when anata is used but in most cases the name of the addressee is preferred.  So when someone wants to ask me the question "Do you eat apple?", he would normally say "Ken-san wa apple wo tabemasu ka?" instead of "anata wa apple o tabemasu ka?"  Sometimes, when the addressee can be clearly inferred, the name is also omitted.

More common expression

Given the two explanations above, the more natural way of saying "I love you" would simply be aishitemasu or its conversational forms: aishiteru (common), aishiteru yo (emphatic), aishiteru wa (female speech).

Now, even if you know that aishitemasu is "I love you" in Japanese, you'll almost never hear it from Japanese.  Unlike Filipinos and Americans who often say "I love you" face-to-face or even over the phone, Japanese generally do not express their true feelings openly.  It is not surprising to hear of Japanese who have not told someone aishitemasu in their entire life.

Some say that Japanese believe actions speak louder than words so they express their love through non-verbal means.  This may be true to some extent but it is more probable that Japanese are simply afraid or reluctant to show their true feelings, not only romantic feelings but other types of emotion as well.

When Japanese try to verbally express their feelings, they use lesser forms of expression.  Instead of saying aishiteru, they would rather say suki desu which translates to "I like you".

More than words and actions

Filipinas in Japan sometimes complain about their Japanese husbands' seeming lack of thoughtfulness for not saying "I love you".  As a Filipino myself, I can understand them that's why I try to encourage their husbands, whenever I can, to be more open about their feelings.

Personally, I believe that expressing love through words and expressing love through actions are both important and that ideally, one should use both means of expression.  However, whether through words or actions, the more important thing is to express love with a sincere heart.