Romantic options don't show up

[ZoCurious]

I was planning on having my Sim marry his grandniece (who is actually slightly older than him). They don't recognise each other as relatives, so I thought there would be no problem. However, there are no romantic options available to them. They are good friends now. They have both been married before, so this has to have something to do with their kinship. How can I fix this?

[Zyffyr]

The game does consider them to be to closely related for romance.

The prohibited relations are :
====================
Grandparent
Parent
Child
Grandchild
Sibling
Aunt/Uncle
Niece/Nephew
Cousin
Great Aunt/Great Uncle   (Sibling of Grandparent)
Great Niece/Nephew  (Grandchild of Sibling)
Step-Parent
Step-Sibling
Step-Child

There is no way to fix it short of using a mod.

[ZoCurious]

Thanks for your reply. I assumed it would be ok if first cousins once removed could get marry, since the level of consanguinity is the same. Ah, I guess I can't keep it all in the family lol

[Zyffyr]

Some of their choices in this matter baffle me, as they go beyond what any society that I am familiar with considers taboo.

[ZoCurious]

Well, I decided that, since my Sim could not marry his grandniece, he would marry her niece. It turned out he could not have any romantic interactions with his great-grandniece either, even though the game did not recognise him as family of either Sims. Therefore, my conclusion is that Sims cannot have romantic interactions with any descendant of their sibling/any sibling of their ancestor.

[SimsSeason]

Step relationships aren't prohibited.