Fushigi Yuugi
Ayashi no Ceres
Absolute Boyfriend
Fushigi Yugi
Ceres Celestial Legend
Sailor Moon
Names are mentioned twice because the series go by multiple names.
Fushigi Yuugi
Ceres Celestial Legend
Sailor Moon
Absolute Boyfriend
Ceres Celestial Legend is a manga where the couple is dating and in a deep relationship. Their are many sex scenes, hundreds of kissing scenes, lots of making out in beds and the couple is living together and in a committed relationship. There are many break ups and it's a mature romance, the manga has sex scenes and lots of making out and the relationship goes much deeper and the couple is dating for a longer time.
Fushigi Yugi the manga goes much farther than the show. The couple is dating for a much longer time, they are engaged and in a committed relationship all throughout the second half of the manga, they are dating for a much longer time and have many more scenes as a couple in a relationship, there is lots more making out and the sex scene in volume 18 is passionate and moving, the relationship in the manga is much more mature than in the show. The Fushigi Yugi manga goes much further and is longer than the Fushigi Yuugi show.
Sailor Moon the manga has the couple in a serious relationship, they get engaged, go from boyfriend and girlfriend to husband and wife, get married, have a kid and have lots of passionate scenes as a loving couple, they were dating in a past life and are dating in the present and get to meet their future kid while they are still dating. The manga has so much more to their relationship and it's much more intimate, passionate and they are dating for a much longer time.
Absolute Boyfriend has the main couple hook up in the beginning, the first chapter, the fantasy part of the series comes later on.
All of these series have couples that are boyfriend and girlfriend and dating and in a relationship during the series, get engaged or married or live together, ahve sex and have a child.