Liz has watched more nests than i, also bald eagles. i have more limited experience. i have watched fewer nest but i think i have watched them rather thoroughly.
i think that the couple owns the nest and the territory together. in the old times people were able to watch the life at nests only from far and for limited times. from far it is difficult to see who is who on the nest. with binoculars it would be impossible to say anything for sure. one would only see that the nest was occupied more or less all the time. by whom, that is another question.
the two turbulent spring seasons 2016 and 2017 were difficult to follow even from the live camera. it took me many weeks of work to find out what happened.
in 2016 Robert returned to the nest but Durbe was gone. Robert got several hopeful and handsome bride candidates who were interested in him but Robert turned his back at them. after a few weeks Robert stopped coming. we never saw him again. without his wife the territory lost its meaning, at least for that season.
in 2017 a similar thing happened with Vents and Shilute. they were together since July 2016. i believe that they were preparing for their first breeding season when Shilute disappeared. Vents waited for her at the nest in vain. also he got new bride candidates but he wanted no-one of them. after a few weeks he stopped coming as well.
books say that if a WTE spouse dies then the remaining eagle finds a a new spouse soon, in the same breeding season, even within weeks. i am not so sure about this. then nest may look occupied by two eagles all the time, but it's impossible to see who these eagles are with only binoculars or even telescopes.
these two examples, Robert and Vents, seem to suggest that in established couples (at least in some cases) the remaining spouse misses the lost partner so that replacement does not happen at once. they need some time of mourning. - this does not mean that they remain widows/widowers for the rest of their lives. it seems that Sulev has found a new wife: Suvi. Sulev was paired with Linda in 2009 - 2013 (maybe even later).
i can't even guess do females take new husbands quicker than males new wives. in the examples which Liz wrote about it happened to be the male who went missing. we have lost females. - Liz didn't mention how long it took before the females took new husbands.
in 2017 after Vents was gone new eagles started to come in random order, males and females in turns. male fought with each other and whoever won tried to take the female who happened to be at the nest as a girlfriend. the males tried to mate with the female at once but all the girls rejected every male's attempts. when a new female arrived she attacked the female who was already there and then the females fought with each other. the winner stayed with the male who happened to be there but they didn't accept mating. only once i remember seeing that a male and a female tried to attack together the pair who were on the nest. (i write 'a pair' because it was not an established couple). there was another attempted attack where there were indications that the attacking eagle was not alone but the female of the attacking pair stayed out of the sight.
altogether the changing of partners in 2017 was like a roulette game where new balls were thrown in the roulette wheel while it was turning around. at times there were several balls spinning at the same time. new balls kicked out older balls, took a few spins with other balls on the wheel and got kicked out in their turn. Raimis happened to stay last of the male balls. he was a fierce fighter. he had two girl balls in a row before Milda kicked out the last of them. there wasn't much "love" between Raimis and Milda in the beginning. Raimis was very hot with Milda but he had been hot with the previous girls, too. Milda banged Raimis in the head almost every time he wanted to mate with her. i think that during the summer they learned to know each other better when their (his) sex hormones cooled down.
in 2016 there were not enough eagles for this roulette game. Egle and Ansis dated long enough to get names. after Egle left Ansis in April (i think) the nest was empty for a while. then Vents came and started to occupy the nest. he didn't have to fight with anyone else than ravens (i'm not quite sure because i didn't watch the nest then). in July he found Shilute and they became a couple. they seemed to be good friends with each other from the beginning.
i'm sorry for the long post.