You're welcome to use the word "trilemma" however you prefer, but it is definitely not wrong to use it to mean "choose one out of three" as here. E.g., here is

You're welcome to use the word "trilemma" however you prefer, but it is definitely not wrong to use it to mean "choose one out of three" as here. E.g., here is the OED's definition: "A situation, or (in Logic) a syllogism, of the nature of a dilemma n., but involving three alternatives instead of two." (The OED gives a number of citations, all of which appear to be pick-one-of-three rather than pick-two-of-three.) The generalization to budgets seems to me to fit better with pick-one-of-three than with pick-two-of-three, too. You're picking p study, q social, r sleep -- and the restriction is p+q+r=1. Picking one out of three corresponds to points like (1,0,0) which are in that simplex. On the face of it, picking two out of three corresponds to points like (1,1,0) which are not. (You could take (1/2,1/2,0) if you like, but that's no longer an extremization; if that, why not (1/3,1/3,1/3)? "X, Y, Z, pick any three.") Separately, I'm having trouble seeing how your married/single/smart/hot/nice thing actually has the structure of a simplicial complex. In a simplicial complex there are three ways (aha! a trilemma!) in which a 1-simplex can relate to a 2-simplex. They can simply be disjoint; it seems clear you don't intend that. They can share a vertex; that would mean identifying "married" (from the 1-simplex) with one of {smart,hot,nice} (from the 2-simplex), and again surely you don't want that. Or the 1-simplex can be a face of the 2-simplex, so that {single,married} correspond to two of {smart,hot,nice}. Again, surely you can't mean that. But what do you want? It seems like you want to identify one end of your 1-simplex with the whole of your 2-simplex, and the dimensions are wrong.