Disclaimer: I don't own Gintama.
It was not a healthy break up.
There's a big fight involved when they decided they can't keep their relationship anymore.
It drove them to devastation and bitterness.
Two years have passed and they still can't get over the hurt they have inflicted on each other and they can't admit it to themselves but they still long for each other.
How they wish they can turn back the time to prevent their mistake.
He is now a policeman gone rogue.
She is now an alien hunter across the galaxies.
How their lives turned sideways they didn't know.
But one thing is for sure, they are still hoping they could turn back the time to where they were happy in each others arms.