you are undermining your wifes authority. I am a step mom and had 2 teenage step kids that did the normal step kid things with me. They could push thier mom around and expected me to be pushed around too. you need to give her discipline and not to be mean she needs to be very harsh in punishment. and if he still does not mind her then she calls you and you increase the punishment for not listening.
if she takes away ex the x box and he plays it anyway she needs to take the power cord from it. and then when you get home to back her up for him not minding you need to swat or ground or whatever you do. extend the grounding for another week since he doesnt think he has to mind her. (ps they will look for the power cord put it in between the matress and box springs)
no kid is going to admit there is a problem because they know there will be discipline if they admit to it. you CANNOT make him respect her SHE HAS TO BE THE ONE TO MAKE HIM RESPECT HER. you just back her decision.
if he doesn't want to do his chores( i used this on 2 teenagers who tried to treat me like thier maid) he is old enough to cook hot dogs so he can fix his own dinner. if he doesnt have to do his chores she doesnt have to do hers. (worked like a charm with a 14 and 16 yr old.) if he cant put his clothes in the clothes hamper she does not wash them. if he cant pick up his trash and dirty dishes she picks them up for him and puts them on his bed. one way or another he has to pick up his own stuff. no matter how long it takes him. she won't have to tell him too in order to sleep he has to clean off his bed. :) My teenage step sons started cleaning without being told after i did this.
and when you get home from work and he is cleaning off his bed ask him why he is cleaning off his bed and make him explain to you it was because he didn't mind her. and discipline accordingly. (you already know the reason he doesn't know that though.) if her tatics aren't working you two need to come up with tatics when he is in bed on how to handle him. have her keep switching tatics with him and keep him guessing what she is going to do next.
if he doesn't pick his toys up let her pick them up in front of you and him and they go in the trash or to a thrift store. take away everything but his bed and clothes out of his room. if he decides he is going to watch tv in the front room anyway have her take away the cable cord while he is at school and until he treats her with respect he doesn't get it back.
I am old fashioned and definately believe in swats. she has to learn to reverse the roles on him. you have to be active in this only you two know what is going on. you 2 have to outsmart him. you know what makes him tick do what he is not expecting. part of this is an age thing. part of this is a step kid thing. and you need to figure out what is the reason he doesn't respect women. you not her. tell her his answer and you two act accordingly. but don't do this in front of him. let her reward him for being good. ice cream or whatever but he still doesn't get his tv back.
Remeber in his mind she is replacing his mother and she is destructing his plans to get you and mom back together. Does he also do this to his mom? I bet he does. if mom disciplines enforce at your house too. make him go to the store instead of her. make him buy the groceries (give him money and a list) wash only enough dishes for you and her to eat off of and make him wash his own. (hide the rest of the dishes leave out 3 of everything. if he is hungry he will wash his own plate or do without. it is now his choice. I recommend to both of you the book tough love. good luck been there and I feel for her and you both.