I can only echo what others have written, there was nowhere near enough emotional impact from the sister's death.
For me it wasn't because she wasn't shown or involved enough, for me it was the weird reaction the MC has.
He grieves for a few days and then it's just completely back to normal?
Paperwork, flirting, sexting. Whatever.
Then there's the thing with his secretary. They kiss and that's it? Nothing, no change in their relationship, no talking about what happened?
And then Sarah wanting to help him forget about his (at that point non-existing) grief, by blue-balling him? That's just weird.
I like the look, the story is okay, but the actual writing seems to be the weakness right now.
It's not an attack, but it seems the dev fails to convey what he wants to tell us/ show us.