Then there were two

Not sure since when but one day i notice there are two birds living on a gap between a pipe and the ceiling on the wall right beside the door of my room.
They always come back at the evening and left early in the morning, try to make it comfortable and call it home by building their tiny nest.





One afternoon I was stepping outside my room and see a little bird's egg cracked on the floor :(
it seems like the tiny thing that should be a new member of the lovebirds' family fell from the pipe before it had a chance to grow.
And about a week or so after that unfortunate incident, i notice that only 1 bird was sleeping there, a day gone by, still there were one, two days, three days until now :(
I wonder where the other one is?