Breeding robins in garden - female now on her own

Hi all, 

looking for any knowledge on robins, if anyone can help. 

I have a pair of robins nesting in my dove house (been here for over a month together) I think they have 4 chicks. They have been very busy feeding and looking after them. I am worried as I haven’t seen him since the day before yesterday. She’s still busy feeding them, then sits in the tree and sings a lot. 

If the worst has happened and he’s died, will she still be able to bring the chicks on to  fledge ? 

Thanks for any help.

this is a pic of the chicks from today.