Ok, I'm working on an creating a fantasy island.

It plays in a similar time like the 17th to 18th century.

Everyone on the island has one job, so he/she can focus on it.

I estimated ~35 Jobs so far which I think are necessary.

Now, every citizen should have a partner, so my minimal population would be ~70, because some jobs require more than one. It's just a rough estimate.

But that doesn't account for deaths of those partners, or a sudden disliking of a couple.

So my question is:

What is the "minimal" population to ensure free(1) partnerchoice of the citizens?

This should factor in:

possible homosexualities

possible no partnership at all (for example the Seaman that does it in a brothel on mainland)

(1) Free means every citizen can in the longrun choose from 3 potential partners.(if this statement even makes sense)

I don't know if this is calculatable :(