she'll come around. she's just in an inner conflict because she lost the initial reason for marrying him. tsukasa does have genuine feelings for nasa now, but due to this sudden reveal she's in an inner conflict with her own feelings.
i'm pretty sure thats a common thing to happen in romance...
well if having a harem is normal in this world (at least for someone of his status) then i can see him having no reason to refuse. doesnt mean he isnt a virtuous person. Ange did have 100 grandchildren in her past life, thats quite the impressive number. so yeah she must have had a lot of kids...