Marcel was beginning to buck under the stress and it was all emotional. There was just so much going on in his head right now; he had yet to find his guns; there was his sister to rescue from his father; the gang to keep in check; and of course, yours lovely Arianna driving him crazy.
So even when he went outside to get air into his head, it didn't help at all. There were so many distractions such as some of his members greeting him and the others that did not acknowledge his presence were busy making out and doing the deed in spots that weren't as isolated as they thought.
Marcel had not felt as emotionally detached as tonight and he needed to be alone. So he went back to his room knowing that Arianna would be busy with the dancers downstairs. For now, he just needed to collect his thoughts.