Present demon slayer time. When Yoriichi found out that Uta wasn't his soulmate he didn't care, he felt bad for his soulmate but he was in love with Uta... until she died. Yoriichi didn't want to find his soulmate after that. Maybe because he was scared of losing someone he loved again... or he just loved Uta too much. If soulmates come in psychical contact with eachother, whether that be bumping into someone or a handshake. Then they will feel a spark and their soulmate mark will glow.