The way I see it is the two things that Jezera values the most are loyalty and competence. Rowan is one of if not the most competent man she knows or she wouldn’t have gone to such great lengths to recruit him in the first place. The fact he killed her father only confirms this, and as previously said might just make him more desirable as a partner if what she said about not caring about her father was truthful. I think if Rowan sufficiently proves his loyalty by slipping further into corruption and doing something big for her, like maybe killing her brother so she can consolidate all the power, she might consider him the perfect mate to continue her dynasty. It’s said that love is needed for demons to have children, getting Jezera to truly love him would be extremely difficult but I don’t think it would be impossible for Rowan if he works tirelessly for her favour.Will there be an opportunity to get Jezera pregnant in future?
Just imagine what wonderful and wholesome stories they could tell their children, “Remember that time you killed my father, I burned down your village and kidnapped your ex-wife, and then you almost beheaded me? Ahh, good times my love.”