Thanks for your reply. A follow up question: I am considering having this conversation you described above involving his parents when they visit later this month. The reason is below and please let me know if you think it is a good idea.
When his parents visited last year, a similar topic was raised by me about removing bicycle from the apartment we were living in, his reaction was defensive at first but when his mother agreed with me, he suddently retreated. He did remove the bike later without any attitude.
I think there might be two reasons why he "listened" to his mother, but not me in this incident.
One, he cares how his family think of him.
two, he does listen to me better when we are relaxing and calm (probably not right before he rushes to work) or when there is an additional agreeable voice in the audience, especially from someone he admires in the family.
You can probably guess that I often need to point out mistakes to him so he has an impression that I am keeping my eyes on his action all the time which most men do not like.
His first reaction to my comments is most likekly going to be defensive under most circumstances because his man ego often kicks in first before his rationality comes in to tell him his action is wrong.
Therefore, his parents being present may force him to calm down to think how to react first before responding.