Amoureux fou (1991)

When Remy, an ad consultant, falls in love with Sarah, the newest star of an ad campaign, sparks fly. The only problem is that they are both married. Sarah's husband knows she will eventually get tired of Remy while his wife just can't let go. At first she throws him out, begs him to come back, cheats on him, hates him, and finally slumps into the worse depression ever. It is amazing what love can do...