This is way too good, and way too human. No one wants to feel alone at the end of the world. You might not like the "cold" lead, but who hasn't made a mistake in their lives?
We can see he actually regretted it and was trying to fix, but once he knew the damage, well, he didn't try, until the end of the world.
I would have love it if the "nice" lead would've actually resolved some of the trauma, but no story is perfect.
For me it was an extremely well done portrayal of real people, with real issues and how we bond as humans.