Hilary Duff and Mike Comrie spend a LOT of time together for two people who are separated ...

We caught up with the parents at the supermarket on Saturday (who grocery shops with their estranged hubby?) with son Luca. The pair bought flowers (quite a domestic, couple-y thing to buy!) and headed home. And it was only the night before that the two were together at Cindy Crawford and Rande Gerber's Halloween party ... as a couple.

But only a month ago, Hil told E! News : "I mean, if there wasn’t a chance for getting back [together], I think we would’ve filed for divorce." Well ...