[MamoruUsagi]

There are a lot of romance series which have the couple dating and in a relationship during the series where they are a happy couple together

Wild Act
Kare Kano
Mars
Bokura ga Ita
Fushigi Yuugi
Kare First Love
The Devil Does Exist
Ayashi no Ceres
Paradise Kiss
High School Debut
Sand Chronicles
Ultra Cute
Happy Hustle High
Sailor Moon
Land of the Blindfolded
Peach Girl
Marmalade Boy
Sensual Phrase
B.O.D.Y.
Missile Happy!
Fushigi Yugi
Akuma De Sourou
Ultra Maniac
Black Bird
Ceres Celestial Legend
Absolute Boyfriend

All these series have the couples dating and in relationships where they are happy together. All of these have then couple as boyfriend/girlfriend during the series, lots of drama, break ups, sex, love, dating, passion. Manga usually has much more dating couples than anime.