Lindsay Lohan and Samantha Ronson spend so much time together that people can't help but wonder if they're a couple. Well, it seems our speculations were right on target, as the two ladies were out in full force coupledom last night.

Lilo and Sam attended P. Diddy's yacht party in Cannes last night, and were together the entire time, holding hands, and being affectionate.

Lindsay seems to have no problem with people knowing that they're a couple, especially after the fit she threw when she saw an Olsen twin just talking to Samantha. What do you think? Are they a couple, or just reallllllly good friends?

You can go HERE to see some pics from last night.