Here is the full list of all 54 Record of Agarest War Mariage Mariage achievements.
Married Piadina.
Defeated Archdemon Eclipse (Soul).
Reached the true ending.
Confessed your love to Piadina.
Defeated Transformed Lifre.
Performed unification with Titania.
Married Saika.
Confessed your love to Saika.
Married every potential love interest.
Unlocked Piadina's Plumage power.
Unlocked Saika's Plumage power.
Reached the ending.
Married Geolette.
Defeated Archdemon Eclipse (Possession).
Defeated Valla Fare of End.
Unlocked Geolette's Plumage power.
Confessed your love to Geolette.
Defeated the boss of Fool's Tower.
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 Piadina for the first time.
Performed unification with Geolette for the first time.
Performed unification with Saika for the first time.
Defeated the boss of Creyu Forest.
Married Panina.
Married Kunka.
Defeated the boss of L'Arc Altar.
Married Felicia.
Defeated the boss of Throne of Ire.
Confessed your love to Kunka.
Confessed your love to Panina.
Confessed your love to Felicia.
Defeated the boss of Fell Sanctum.
Defeated the boss of Rauea Mountain.
Unlocked Panina's Plumage power.
Unlocked Felicia's Plumage power.
Unlocked Kunka's Plumage power.
Defeated the boss of Meren Marsh.
Defeated the boss of Zula Desert.
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.
Defeated the EX boss of L'arc Peak.
Married every potential love interest?