Blackcap Mystery

Just after the snow had melted here, I saw a new bird appear in the garden - grey with a brown hat on.  I couldn't for the life of me work out what it was, until three days later when another new bird appeared - grey with a black hat on.

Well, once I'd worked out what a male blackcap was, I could identify the female blackcap who came first.  There was a couple of days when both the male and the female would appear in the garden together, but for the last week the male has been here lots but the female hasn't appeared at all.

Can anyone speculate as to what might be going on? 

Are they a pair? (I had presumed so, but having just read about the steamy sex lives of dunnocks, I guess I shouldn't jump to conclusions!)

Could the female already be nesting somewhere nearby, and the male bringing her food?  (Though he seems to eat everything in sight, so I think it's doubtful.) 

Has the male driven the female away?  Or might she come back again a bit later?

I thought maybe the blackcaps were just visiting because of the cold weather, like the redwings.  But the redwings are long gone, and the male blackcap seems to have made himself at home, and I see him every day.  I'm pleased to have him, though I don't think the other birds are so keen - he's not exactly the caring sharing type where food is concerned.  The other day I saw him chase away two robins and about seven starlings - and I thought anyone coming between starlings and their lunch was a logical impossibility!