To me, Y/N is like a reflection of Kratos in a way. A story of reconciliation. As for Y/N and Anna's relationship in the future, the song "To Be Better" by Miracle of Sound fits so well

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Break the hard chains of fate
Roads we walk we create
For our futures are wide and vast
To respect and respond
To add strength to our bond
Cast the fury into the past
I can choose to be better at last
Through all the pain I've grown
Warm up this old heart of stone
Leave the hurt behind
Tearing the threads of the tethers
Leave the hurt behind
We can choose to be better
We can choose to be better
Crush the bones of despair
In the jaws of the bear
Prophecies may come to pass
Keep the beast deep within
Always under the skin
Let it claw through the mirror's glass
I can choose to be better at last
And even a heart of stone
Can warm when no longer alone
Leave the hurt behind
Tearing the threads of the tethers
Leave the hurt behind
We can choose to be better
We can choose to be better
In this winter of woe
Seeds of hope they still grow
Sheets of white over rock and grass
From contempt I have turned
Now I'm just trying to learn
Burning skies now overcast
I can choose to be better at last
Leave the hurt behind
Tearing the threads of the tethers
Leave the hurt behind
We can choose to be better
We can choose to be better

Now think about it, both joined the military out of a mix grief of losing their families and wanted revenge