This VN is fairly linear, so yes, the only ending of this update is the one with the Mum/Karen. However, we don't know what the MC is going to do in 0.9 or future updates with regards to Haley. Some speculation that this game might go with a harem route and have the MC enter into a polyamorous relationship with his Mum, Aunt Nikki and Haley but it could equally end with the MC ending up with just one woman or any number of different outcomes at this stage.
I personally am firmly in the camp of wanting the MC to eventually dump Haley for his Mum because she's so much hotter than her and, you know, it's his Mum; can't get much better than banging a hot, sexy family member. Also would like to see Nikki and Haley get it on without the MC, maybe become a lesbian couple despite what Nikki said about preferring dick, as not only would this be super hot but it could actually help the MC when breaking up with her as she might want the same so she can be with Nikki.