For Brigitte, it's slightly odd.
What I can advice you to do is go step by step. Play game with her but instead of actually playing, go all the way with whatever raunchy option it asks you to do. If you see the scene of MC fingering her while she's ontop of him, you're set for that scene. Visit the next day and choose the "Sit Near" option. There'll be a "Footjob" option. Pick that and as the option states, Brigitte gives MC a footjob. Once all that is done, the option to fuck should appear but it's another step.
Go and visit Brigitte at about 0100 onwards. She'll appear infront of her door naked and tease MC about it. Just keep repeating it till she asks MC for sex and then you should be done.
You don't have to have sexual relations with the PE teacher to even get it done.