I just feel Luke's closest friend is a lesbian. He genuinely cares about a woman and sex is off the table.
I can't sleep so I watched the bit again with the news of the bombing:
....Moira says, 'luke hey, where you going?'
Luke, 'Home, I'll get dinner'
Moira, 'you don't wanna know she's ok'
Luke, 'she's not ok'. -Long pause-. ' she's alive. Have faith she's alive.'
Moira, 'That's not knowing.'
Luke, -look of sadness- 'See you at home'....
Clearly he lives in limbo and the bombing could finally end that.
At this point both don't know their partners are alive or dead so a bit of hypocrisy?
When Moira says, what will I do if she's not dead. He says, welcome to my world. Is this the impetus for her decision to track down her partner.
Luke seemingly wanting to keep faith seems caring. Being dramatic at this point would make her pain his. Rather he quietly acknowledges his struggles.
It shows the contrast of not knowing because you cannot choose and not knowing because you choose. Moira is now grieving but Luke is still in the same position. Him going to get dinner shows the banality of every day interminable hope/dispair?