I was once in a relationship where my SO & I got in the "habit" of always fighting about everything. I finally had enough and made the conscious decision to stop - to no longer engage in that type of behavior. It was difficult on her, but she eventually learned, once I wouldn't engage her any longer, to change her approach and we finally began getting along.
If you want to have a better life and you feel W is immature, then it may be up to you to show her the way. Lead by example.
It takes hard work and a lot of will power to avoid habit fighting over nothing. However, you can change the course here by choosing differently.
Small steps here. First one, cut the fighting.
"Nobody can go back and start a new beginning, but anyone can start today and make a new ending." - Maria Robinson
M: 45 WAW: 36 T: 17 M: 14 Kids: D9 ILYBNILWY: 6/2010 W left: 2/2011 W back: 2/2012