I think this is the moment when she entirely regains trust in him. She realizes that wherever he was, he was scared and confused, and yet he took the time to record something for them, for her. To let her know he loves her, and he never intended to leave her. I think this moment was so beautiful.

All 7 Seasons of Castle Summed Up in a Few Lines

Season one:

Beckett: “YOU ANNOY ME BECAUSE IM ATTRACTED TO YOU”.
Castle: “I would totally bang her.”

Season two:

Beckett: “Fuck I’m starting to like him. But I’m scared and I doubt he likes me.”
Castle: “I like her. But she must not like me. I must get over her.”

Season three:

Beckett: “Stop liking him. Stop liking him. Stop liking him. But I will be as flirty as possible to torture him.”
Castle: “Fuck I can’t stop liking her. I think I love her.”

Season four:

Beckett: “I love him. But I’m terrified to love him. I’m too damaged to love him.”
Castle: “I will wait for her. But I can’t wait forever.”

Season five:

Beckett: “I just want you.”
Castle: “I love you. Always.”

Season six:

Beckett: “This man is my soulmate.”
Castle: “This woman is my soulmate.”

Season seven:

Beckett: “I will always be here for you. Keep me close.”
Castle: “Always.”