Mary Kate Olsen and boyfriend Nate Lowman made the party rounds at The Art Basel Convention in Miami, and left quite the odd impression in their wake. Partiers noted that Mary Kate wasn’t looking very healthy and started a hiss-fest fight with Kirsten Dunst.

more nasty news after the hop…

On Wednesday night, Olsen and Kirsten Dunst got into a heated argument while sitting together at Audi’s party at the Delano in South Beach. “They just kind of stared at each other for a long time and then started exchanging nasty words,” says an onlooker. “Then Olsen just got up and left. She’s been going really late every night. She looked like she had not brushed her hair in a week and she was chain-smoking the entire time and sitting like a sourpuss with her boyfriend. She was acting very oddly.” as told to Page Six

With all the partying and chain-smoking I guess we can cross “prospective mother” from the list. Maybe it’s just booze bloat?

Photos: PR Photos