Being another player's Companion and having that lead to sex could TOTALLY create that kind of double trouble. Fucking, however, is usually done offscreen, rarely with only one person. If I were MCing, having a Fucking gig and having sex with another PC would mean you'd handle the PC sex onscreen, even if you negotiated some barter for it, and the Fucking gig would represent trying to get some tail on the side. The obligation gig would then be about keeping the other person happy while the fucking gig still represents keeping others happy, and juggling those two makes total sense to me- it just makes the catastrophe more fun/easy when it does happen. Clear as mud?