I went into this one already knowing about the travel bug, but even if I hadn't, "No more negative sentiments and must be friends" isn't particularly hard to check manually, so that bug wouldn't have frustrated me. It also helped that I used fresh library copies of existing sims in a What if save, so I was already attached to those characters. With new sims it probably wouldn't have worked (as in: been over in two sim hours of mechanical pressing buttons in the friendly pie menu.)
The biggest problem was to make the two sims interact. They were stuck together in a big house with free will off, so they could easily avoid each other. Then at the end of the first day Sim A ate Sim B's ordered food. Now that was a reason to interact, but in a negative fashion. I had to force myself not to make them brawl.
I let Sim A apologize and the next day made sim B give a romantic gift to A. Then I waited what they'd do and the receiver of the gift chose to continue down the romance path. After that point I helped the two with flirty moodlets from the TV and food. By the end of that day (and after three woohoos) they were Enemies with Benefits. It was easier to get that status than I remember, probably because we now have a crapton of ways to add positive moodlets.
Here's the full chronicle: https://forums.thesims.com/en_US/discussion/comment/18024014/#Comment_18024014
You'll notice that only 4 posts cover the challenge gameplay, whereas five deal with the sims living without interacting and then the aftermath.
Was it a challenge? No. Was it fun? Yes, but not because of the idea, but because of the spin I put on it. Could just as well have been another simmer nudging me to play this particular story hook. From official scenarios I expect something more meaty, like the whole town hating you for being a crimelord's kid and your sim (or little gang of sims) can either confirm their opinion or redeem themselves.
