Actually called Sasha his beloved. Poor kid, reality is going to hit him harder than truck-kun
Eh there is a chance that if he actually manages to make her his girlfriend she will stop sleeping around since she does seem to care about that kind of thing.
Through I dunno if the author would go for something so vanilla, her continuing to sleep around after they get together so that she can tease him and make him rail her even more could be final result just has easily.(And him not really caring much because he knows that she loves him the most).
Or we have the third option, the fat ass becomes canon and appears on the last chapter and then we just know that master lost because he will never be Sasha true love if the fat ass is on the picture.(I kinda wish this one happens, if would be hilarious)