I think the game-author has a very black humor (and nice, that there are some hardcoded game-ends)... you are not able to do all you want (and thats like real life)... you have to decide how to seduce/abuse your romance/victims.... counter the tricks of both women (they are cunny)... be aware of Bill... you will very quickly learn the drill
and playing with the cheatmod will give you a lot of opportunities (just save before critical points, so you have room for errors/reloadings), the walkthrough is a great help...
and from reading all the dialogs and mini-sequences of the version 9.0 there might be an interesing ending of the game... like slavery from Bill, captering the sister of Mark... and Mark has to decide, which side he will be on... on Elana (undercover cop?) or on Bill's... even "training his sister"... a nice ending would be helping Elena... afterwards living in Bills House with his sister and Christina... visiting randomly from Elena... lots of possibilies for lesbian training, triangle, quadruple... and since Mark is not the brightest under the sun... ending with babies from each of the 3 women *laughing