fair enough. can't find a rule against marrying ruler and heiress as a prospective consort, although historically it normally happened after the death of the first spouse.
however, i also stumbled over the 777 rule, which requires the marriage partners to have a date night once every 7 days, a weekend trip every 7 weeks and a romantic holiday every 7 months.
they would have to make a proper schedule or share date appointments.
keeping in mind that the females in this relationship are the providers with a dominant role, the protagonist would take on household duties and family care.