The classic rock band the Beatles played a lot in Hamburg at the start of their career and thus felt it was important to release some of their first recordings in German too. The song "She loves you" was also released in 1964 as "Sie liebt dich," and you can listen to it here. The expression is also the climax of a classic fairy tale:
Oh, Biest! Ich liebe dich. Es ist mir egal, wie du aussiehst.
Oh, Beast! I love you. It doesn't matter to me how you look.
Caption 84, Märchen, Sagenhaft: Die Schöne und das Biest
And another classic German expression for being in love:
Ich habe mich in dich verliebt.
I've fallen in love with you.
Caption 31, Filmtrailer: Keinohrhasen
The phrase in sich verlieben is one of the times when the German preposition in has the noun following it in the accusative case. In the Berlin dialect, it is often in the dative case (ich liebe dir, ich bin in dir verliebt), but this is not good High German. Let's stick with ich liebe dich and ich bin in dich verliebt!
Nacht, mein Schatz. Ich hab' dich vermisst.
Good night, my precious. I've missed you.
Caption 4, Mama arbeitet wieder: Die Trennung
Der Schatz is a classic German term of endearment, but it also means "treasure." When I lived in Germany as a teenager, I often heard male American soldiers using the dialect version of the word, Schatzi, to accost unfortunate female passers-by. The word "schatzi" is even included in a number of American dictionaries as an acceptable English word, evidence of a relatively recent addition of a German word into English. And of course, if you love someone, you miss them (vermissen) when they are gone.
Look for further examples of lieben and verlieben on Yabla German and see how they are used in a real world context. PS The Beatles also released a German version of "I Want to Hold Your Hand" as "Komm, gib mir deine Hand"...