Michele and Hans in the Museum??

Well, my personal interpretation is the following:

Hans has nothing to live for now that he boinked Michelle. It's not likely that she will leave Alex for him. So he decides to kill himself because there's nothing really to live for. And what better moment to die than after boinking Binoche?

Alex is a tough kid, he grieved I'm sure, they just didn't show it, because if they had it would be like "Oh, he's dead, let's show alex grieving so the audience can sympathize", and I don't think there was any of that kind of thinking behind the editing board, or shooting.

Prior to the musuem scene, Hans tells Michelle the story of his life. How he had a wife, a job, an apartment. But his daughter died, and his wife suffered to death with grief. She died at 33, looking like she was 50. He didn't know what to do, he just watched her die, because she put her pain between the two of them.
Yes Hans was fondling Michelle's breasts at the museum, one last contact with female flesh before he decided to end his life [after all, what was he living for?] but it has nothing to do with him being in love with Michelle as the poster above suggested. He said it, women have no place in the 'sans-abris' [without shelter] community, they are beaten and raped. He kept telling her to leave the bridge because she didn't belong there. She needed to live her life.
Why did they not grieve him? I guess they simply understood Hans's decision.
I love this movie. It just epitomizes Paris perfectly for me.
I wanted to add this quote from the movie, since there are no quotes on this page: it's the prison scene where Michelle goes to see Alex, she says:

Mais depuis des semaines presque, j'ai des images de toi, c'est pour ca je suis ici. Ce sont les reves qui m'envoient. Les gens qui sont dans nos reves la nuit, faudrai toujours les appeller le matin au reveile...la vie serai plus simple.

<But for the past couple of weeks approximately I see images of you, that's why I'm here. My dreams send me. We should always ring the people in our dreams the very next morning...life would be more simple>
Sorry, my personal translation:p

it's a dirty world Reich, say what you want

I believe that Hans' intentions were not crude disturbing. I believe he preempted that he was going to take his life and spending that femininity Michele was simply a last embrace before he left the earth.
Earlier he had mentioned that Michele reminded him somewhat of his wife and I think he forced her knowing that soon hear going to be with his wife.
I don't think Hans loved Michele. In his own way he cared about her and felt strongly that she lived her life and made something of herself.