These two birds are likely not a pair. Male hummingbirds mate with females, but otherwise are not involved with the females, who nest and raise the children alone.
Hummingbirds can be territorial and scare off other birds, including other hummingbirds, from the flowers they frequent. In this shot the birds are sharing the feeder nicely, and evidently must share the nectar with a bee.
This week we are showing nighttime photos of Budapest on Viva la Voyage.