This film by Fritz Lang, from 1945, is essentially domestic noir -- the story of an unhappy, ordinary middle-aged married man led into a life of deception and, ultimately, crime by a fetching femme fatale. It was Lang's favorite among the films he made in America and has a considerable reputation but I find it curiously dead emotionally and lacking in real suspense.
The problem is that the fatal femme is so obviously on the make, so obviously not attracted to the ordinary man, so cynical and so dumb, that we feel only pity for the guy, a pity laced with scorn. We can see what attracts Walter to Phyllis in Double Indemnity -- the two are hot together -- and even if we suspect that Phyllis might be using Walter, part of us thinks it might be worth getting used by a woman like this. This implicates us morally and emotionally in Walter's transgressions, makes us care about his fate.
It's impossible to care about Chris in Scarlet Street on that level -- watching his life come apart at the seams is like watching a train wreck from a distance. It's fascinating and horrifying but we're not involved. In Double Indemnity, like it or not, we're passengers on that trolley hurtling towards the end of the line.
The ending of Scarlet Street achieves a kind of tragic power, because things go so horribly wrong, and Chris's moral collapse is so complete and so bleak. It's not a genuine tragedy, though, because in a genuine tragedy we could imagine ourselves in Chris's place. In Scarlet Street we're denied that identification, that implication in his fate.