Black Widow (1987)

Theresa Russell is the Black Widow, named because of her proclivity for finding a mate and killing him shortly after his usefulness expires. Unlike the spider, however, the 'usefulness' isn't post-copulation but post-marriage, once the will has been amended to leave everything to her. It's unclear what she actually does with the wads of cash she acquires, though.
Federal investigator Debra Winger tracks the killer in a manner not dissimilar to how the killer tracks her prey, each woman succumbing to an obsession that's only really different in its focus.
The journey contains within it a number of things that are implied but not clarified, so it's up to a viewer to decide if the subtexts they thought they read were actually there or if they were accidental, surfacing in the edit.

3 green windows out of 5