Male Zebra finch pulling feathers from female?

so like, i have a female zebra finch and a male. they're in a cage about the height of a table and the width of a cabinet. i give them enough food but the male zebra finch occasionally plucks feathers from the female one but then i see him going into the nest and leaving them even though i give them material. should i separate them before she dies or should i leave it alone? other than that, they get along, they sleep together and it doesn't happen often. but, today i've seen him do it like 4 times in a couple hours.