You have had some extremely good advice so far YWIW, here`s some more.
Don`t spend so long at the airfield. Wives will accept a half day rather than all day much better.
Have you considered taking her with you? Depends on the airfield/Club. Many in the UK are slums from whichever direction you approach.
Join the PFA and your local Strut. If it`s any good they should have a `spare seat` program so your wife can go along for the ride too and see what future adventures there could be.
Sorry to keep on about your Wife, but she is the second most important aspect of the whole argument. If she does not like/ is not interested in flying, you will NOT change her mind. Just accept it and try not to make your flying break up your marriage. You have heard of AIDS....Aviation Induced Divorce Syndrome. It`s very potent, look around your club.
Keep going, however slowly, your situation could change, OR give up entirely and never look at the sky again. There should be something around called Aviators Anonymous because once it`s got you it does not let go.
Regards
Mike W.