marriage with an age gap

marriage

a wall socket; an outlet

root / base, foundation

navy blue

混入: the act of mixing; the state of being mixed; a mixing or mingling of two or more things, typically in an undesirable way

混入: to mix one thing into another, typically in an undesirable way; to mingle, to become mixed, to get mixed, typically in an undesirable way

懇切: kind; exhaustive

懇切: kindness, cordiality; exhaustiveness

婚約者: fiancé or fiancée