Apologies for the late response.
So I am a little bit torn in exactly what to respond to. My inclination though, is to lean towards the more musical aspect of Wagner's piece, and express my views on the piece in light of some of the other comments. I guess to start, I agree that there certainly is a lot of tension that builds in the Wagner piece through the use of dissonances like suspensions, and including tonally ambiguous areas and trajectories. However, I am not sure if I yearn for an ending and a resolution as much as it seems some others have while listening to it.
As Hillary writes, the music continually pauses on the dominant in the beginning, and although, perhaps, not as satisfying as resting on the tonic, or completing a cadence, I think it does give the piece a bit of room to breathe and feel a sense of relief, even if it is not entirely there. And on a small sidenote, I would disagree that a piece has to move from dominant to tonic to feel resolved. Although the system of Western tonality that we see here which enables tension and resolution is based on the leading tone of the dominant leading to the tonic, I think there are some jazzier, funkier options of cadencing that don't end dominant-tonic. Moving from the dominant 5 chord to a 4^7 chord, for example, although perhaps a bit unsettling and seemingly incomplete at first, resonates for me as a beautiful, complete, and satisfying cadence. But sidenotes aside, I think there is a certain beauty in the way Wagner delays and puts off cadences, and how he plays with dissonances and resolutions. In one class earlier in the semester, someone mentioned that sometimes- almost paradoxically- you do actually listen to "sad" music because it makes you sadder, and you want to almost wallow in that emotion even though it's not necessarily a "positive" emotion. I think from this piece, I was sort of enveloped in the emotion of it all, and the sort of longing and yearning, which is perhaps why I did not seek the resolution as strongly.
Finally, on the matter of whether or not the piece can embody Schopenhauer's philosophy, or merely embody the emotions behind his philosophy is difficult, and I'm not sure exactly where my opinion falls. However, I think either way, in listening to the tension and resolution (and lackthereof), there is a clear and an intimate relationship between the two.