Hey. I recently completed a run with expansions for this category. As of right now, it has not been verified, but you can see it on my youtube if you need to. My run with expansions was 1 hour and 26 minutes. I'd assume that this run would be sub 3 hour without expansions.

What I did was make a club with woohoo as one of the things the club likes to do and invited everyone that I could to this club. When I ran out of people to invite to the club, I went into town, and into people's homes so I could get to know them, then invited them to my home to get them to woohoo with my sim.

The aspiration and traits you should use for your sim in both with expansions and without is one of the romantic aspirations, then outgoing, romantic, and cheerful for the traits.

For without expansions, I would go into towns until I met 50 or more young adults/adults/elders, then go back to your house. Invite each sim over, befriend them (Befriend them more then other sims if they are not single), then get them flirty with by a pickup line, giving them a rose, or kissing their hands. Grow the sims love with each other until around(ish) 1/3 of the way up the bar, then woohoo. Then, you can ask them to just be friends (you probably don't need to), and ask them to leave, then move on to the next sim, or fill up your sim's needs. Side notes: When you start the game, it would be better to buy a better double bed so your sim doesn't get uncomfortable from a cheap bed. Remember to only invite sims over daying daytime (Around 7:30 A.M. to 10:00 P.M.

This is just what I figured out after a few hours of research/messing around in the game. A lot of it could be wrong, or slow, so just use this as a basic guideline.