he said sunday, you did something sunday. What is the problem ?
I don't think this is a french behaviour. It's your boyfriend who's like this, who's not stressed and who enjoys slowly his life.
By the way, as kiwi said , "go with the flow", it's more funny. 8)
Et pour Mlle guest, je t'ecris un mail de suite. Par contre, je dois etre un peu jeune pour toi.