Another easy one.
I created a household with 6 sims, had all their traits the same or similar(romance and outgoing).
I had a female and 5 males, all males were elders, put relationship status as wife to one of the males. Moved in to a home, had the husband and wife woohoo until he died. Became friends with next victim while mourning, when able to married, then woohoo'd to death. Repeated until all were dead. I did turn aging off.
Not sure if this matters or not, but had all extra sims working, made them quit their jobs when it was their turn. Made it easier to concentrate on the relationship I was trying to work on.