If you need somewhere to contemplate leaving your lover, go alone, and if you don't mind them not being there to share something sublime in a glass or a dish, you have your answer.
There's a few secondhand clothes stores in Paris, but always immaculately selected, expensive and fashionable. Guerrisol however is a huge, dirt cheap jumble sale. Stock seems to rotate daily in each of their four stores, and prices fluctuate on the hour. Sifting through endless rails of synthetic jackets at €3 can suddenly reveal a hidden gem.