If A cannot live with her and absolutely wants B then Talk to B, and say not do do so, if B still does it then Leave her. If the shoes absolutely does not fit your feet then why were it, your feet will be in pain all the time and later will destroy your feet. Thinking that shoes will fit your feet after walking with it for few days is only true if the differences is small not if the difference is of one or two number small. For those who understands very little, I am not calling women a shoes (As our culture still has this mentality of looking at people, either shoes or the hat), but just giving an example, for this answer goes also to those girls who have the same problem with their man. Peace....