Maxwell waited until the next morning to tell Andrew what was going on. He had spent the rest of the day complaining and lecturing Richard, while also taking care of him. From those actions alone, Andrew learned too much about what happened.
With that said, Andrew was happy for Richard, even if Maxwell was pissed. The man got laid.
Good for him.
Maxwell, because he was an omega and had always been an omega probably didn't realise that things were a bit different when you were a beta. If things had gone down like Andrew assumed, there might be some kind of delay with Richard's body. There had been a delay with Andrew, so it was an easy jump in Andrew's mind.
Andrew was fairly certain that Maxwell also made that assumption, but far later then Andrew did. Andrew didn't mind. He had some Christmas baking to do for Christmas eve and Christmas morning. He wasn't about to show up to anyone's house empty-handed.