No stamp when entering France from UK [closed]

You mention that your wife isn't European, so I will assume that you are.

In this case, you should be applying for a residence card issued pursuant to the free movement directive, and in that case the absence of an entry stamp is of little consequence. The one related factor is that the application costs €25 if she has been in the country for less than three months, and €340 if she has been there for longer. So you will want to be able to prove that she was outside of France at some point, but you can use any evidence for that (and I suppose your statement of her date of arrival is probably going to be sufficient).