Here is the full list of all 54 Record of Agarest War Mariage Mariage achievements.
Married every potential love interest.
Married every potential love interest?
Reached the true ending.
Defeated Archdemon Eclipse (Soul).
Defeated Transformed Lifre.
Married Piadina.
Defeated the EX boss of L'arc Peak.
Performed unification with Titania.
Confessed your love to Piadina.
Married Panina.
Confessed your love to Panina.
Married Geolette.
Confessed your love to Geolette.
Married Felicia.
Confessed your love to Felicia.
Reached the ending.
Married Saika.
Defeated Archdemon Eclipse (Possession).
Defeated Valla Fare of End.
Confessed your love to Saika.
Defeated the boss of Fool's Tower.
Unlocked Saika's Plumage power.
Unlocked Piadina's Plumage power.
Unlocked Geolette's Plumage power.
Defeated the boss of Geluire Woodland.
Defeated the boss of Star Point.
Defeated the boss of Frost Mountains.
Titania joined your party.
Defeated the boss of Verde Cave.
Defeated the boss of Gedecht Plateau.
Performed unification with Saika for the first time.
Performed unification with Piadina for the first time.
Defeated the boss of Creyu Forest.
Performed unification with Geolette for the first time.
Defeated the boss of L'Arc Altar.
Married Kunka.
Defeated the boss of Throne of Ire.
Unlocked Panina's Plumage power.
Confessed your love to Kunka.
Defeated the boss of Fell Sanctum.
Unlocked Kunka's Plumage power.
Unlocked Felicia's Plumage power.
Defeated the boss of Rauea Mountain.
Defeated the boss of Zula Desert.
Defeated the boss of Meren Marsh.
Doze joined your party.
Defeated the boss of Raster Valley.
Cupra joined your party.
Defeated the boss of Hell Maw.
Performed unification with Panina for the first time.
Performed unification with Kunka for the first time.
Performed unification with Felicia for the first time.
Defeated the boss of Dozy Forest.
Defeated your first opponent.