roosting of lovebirds breeding?

by nizam
(calicut,kerala,india)

i have 2 peachfaced lovebirds. i dont know anything about their age. i bought that from a sho and he told that one is male and another one is female. i have a good cage and a nest. 2 lovebirds are always together and sometimes they both will go to nest box. i didnt ever seen their mating..
why they always go to nestbox together?
are they going to breed?
are they roosting inside?