Leaving the lover boy to his soon to be bride, Seth pulled his soul from the temporary vessel and transferred it elsewhere. It wasn't time to return it to his original body, that could simply exist as a puppet for the time being.
Instead there was something else that required his full attention and presence, even if this was supposed to be the time he was spending with his boys. He didn't really get a day off anyways.
It was a little surprising to hear about Alfie's decision, but according to the Matriarch he had declared his feelings in front of everyone, not once but twice, in the traditional way. The first time had startled her enough to stop her execution, and the second was like a confirmation of what he had said.