I believe one thing going on in this movie is paul is a spy of some sort. probably originally from military intelligence.
he is extremely athletic (especially for a middle-aged hotel manager, I know whereof I speak lol), easily moved to violence, very good at eliciting information without giving information. this is probably why it affected him so deeply that rosa kept secrets... he didn't think he would miss something right under his nose.
of course, I think rosa had (past tense) a similar line of work and this is why she was kind of... not o.k. she perhaps needed to retire... maybe even paul did, but I think it's more likely he's just the type who only comes in so often.
marcel has some sort of sketchy background as well because he, too, is very athletic. both marcel and paul tend to dress and act in a way that seems more suitable for their age (when they're in public... tango competition and ass-beatings excepted).
this makes me think rosa WAS murdered even if paul doesn't realize it (and he doesn't, but then he was the prime suspect). perhaps the police were told to declare it a suicide and move along.
so... perhaps jeanne didn't cross his path by accident? he doesn't try to check up on her. she's too immature to be up to something on her own, but there's the weird counting, etc.
however, even if that angle is discounted on jeanne why does she shoot paul? to get rid of him?
allen tdg (who just watched this) forwarded the theory that she didn't (mean to) shoot paul; she meant to shoot her father/the colonel. so, she was in shock a bit that she did it... although she didn't much want the reality of being WITH paul.
there's a totally for crap analysis of this movie from 1974 that just proves me theory that people in the 70s were stupid. and that e.ann kaplan didn't have much use for marlon brando. basically, she's p.o.ed that he didn't explain the movie to her. um... he acted it out, wtf else to you want? plus, he's not in every scene anyway. there's a whole different storyline...
and she misses the fact that ROSA is a huge influence on a lot of what happens even though she only appears in one scene as a dead body. so there you go.
check it out and see if you agree with me or the evil ann. hehe