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