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