can someone spoil me as to why he was acting so distant in the beginning

For abit in a panel in the beginning, there was a ring box. I'm just assuming it's a ring. I guess he was busy looking for an anniversary gift, so he kept giving excuses. Then when he met with his siblings it was mentioned that he asked for help in picking an anniversary gift. And I think MC, given his dementia?, thought it was their anniversary on a wrong date.
And ML wants to sleep in different rooms cause he keeps wanting to do it with MC