Duck favoured by both drakes

I am concerned my Cayuga female is being overmated. She appears in good health but often separates from the flock.
We have 1 Cayuga drake and 2 females, 1 welsh harlequin drake and 2 females that have been raised together since hatching, just over a year ago. I understand that a 3 to 1 ratio of hens to drakes is preferred but we lost 2 hens to predators last summer.
In this case, more females wouldn't offer her much peace since she is the preference. More hens that are just ignored won't change anything.
Mainly the WH drake pursues her aggressively, and especially when I let them out of the coop in the morning. They free range and head over to a small pond/large puddle on a vacant lot next to us. They forage and swim freely (with permission from the owner) and just consider this an extension of our land. While they are out and about, the drake doesn't harass her but when they return to the coop for a midday snack of feed, he'll be at her again. She dodges, runs and avoids him but when he does mount her, it attracts the attention of my Cayuga drake and he'll peck her head while the other drake is atop her. Sometimes he will also try to mount after the other drake but at least he is less persistent than the WH drake.
She was often the one lagging behind the flock and earned the name Lost, as she would quack to find the rest of the them after doddling too long. But now it seems she's deliberating leaving the group and keeping a greater distance from the others- only sometimes though, mostly they stick together and like I mention, when they are in their swimming hole or the field, I don't observe this behaviour.
She seems healthy and no loss of feathers. Do I need to be concerned for her? I also have no idea what goes on at night when they're confined to smaller quarters and she'd have less ability to evade him. No signs of excessive feathers in the morning (good sign). Although, late winter this was the case- many feathers, mostly from the WH hens and those girls were looking a little battered. In that case, I separated the hens and drakes but their hormones died down quickly and I didn't have to segregate them for more than a week. The process of catching the drakes stressed them al so I didn't want to do it for longer than necessary.

Thanks in advance to the more experienced duck keepers than me, that may have some advice.

Well, you can either remove one drake from the flock or leave the status quo and hope for the best. The thing that concerns me is the drakes tag team mating her on the pond and the possibility that they might drown her - a frequent cause of death.

Well, so far she's safe in that regard. The aggressive pursuit and occasional, subsequent tag-teaming only occurs near the coop. So far it doesn't seem too often but this is only what we've observed, I'm sure there have been incidents we haven't witnesse. but it's almost like the WH drake gets nutty when he is outside of or near the coop. They pile out of the coop, single file duck style, waddling in a row at the same speed. He hits the dirt and goes after her. Same when they are coming back for a snack- ducks all in a row, gets to a certain proximity of the coop and he goes after her again. We've also seen him pursue her other times but still only within maybe 100 ft of their home.

If she starts showing signs of lameness, I would remove either her or him from the flock if they were mine.