It could mean that you're seeing your wife in a different light. That you may be feeling she has changed in some way.
Using a toilet represents something in your life that feel the need to be rid of...old habits, thoughts, attitudes, emotions, etc.
White is feminine. Symbolizing virginity, purity, well earned success, honesty, virtue, innocence, peace, happiness, joy, transformation, cleanliness, dignity, awareness, clarity of mind, hope, and light feelings, but also emotional coldness and immaturity.
White in a dream might possibly be a reminder to resolve special situations and problems.

Is there anything your wife has done recently to change your view of her?
Is there something in your life that you feel is wasteful, and that you'd like to be rid of?

Hope this helps, good luck!!