I’m not so sure. Angst, to my mind, is a generalized feeling of hopelessness, dread, and anxiety. The narrator of Paint It Black has a specific and explainable reason for his state (the loss of a lover).
Also, I never considered it as a teenager’s viewpoint.
I always have, largely because feeling the sort of intense, all-consuming despair over lost love portrayed in the song is very typical of teenagers - although obviously not restricted to them.