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