Rereading this allows some insight, such as looking at this from the psychological, or maybe psychiatric, point of view. If you think about it, Almus has been through a lot, including killing people and winning a war. He has been bearing a huge responsibility for years. One mistake from him could have resulted in the deaths or enslavement of scores of people he liked and who depended on him. Yet he used to be nothing but a regular dude in Japan.
Many comments here, and no doubt some of my own comments in the past, don't really take this into account. But logically thinking, all of it must have changed him majorly as a person, even down to endocrinology. I bet he has now constantly more testosterone in his blood than he would have had in Japan, due to all the physical activity and the necessity of being a great leader for his people (in a macho culture). That would have also driven him to embrace Yuria, even if his original self back in Japan wouldn't have, under similar circumstances).