I had that problem with my girfriend i know, it may not be the same but hey if it help me maybe it will help you too.
I've always been in sports so like you it was about improving the way i looked but also endurance. But she started to be a real pain in the ass almost asking me to decide the workout or her. So i try to analyse what was going on hr head, and later on we talk about it.
1) She saw that me trying to improve would change the way i feel for her (ie going for someone hoter)
2) I would spend much less time with her
3) i was bored of her and working out was my scape goat.
So what did i do? I talked to her, and i made her part of my training, helping me, and also training side to side with me. At the end she started having lots of fun especially when i dragged her on a tire around while running (like running with weight) or when i would run with her on my shoulders or when she got to punch me or learn submisions. Also i would switch to playing tennis, basket, soccer to not have the same workout or same activity.
I also made her understand that the decision i made was so that i feel better (healthy and mentally) and if anything i was doing it for her etc etc. So talk to her and made her part of your effort to change yourself, i know they say that they like just the way we are but like my gf said "adding some six pack does not hurts either."
So let her know what is going through your head, women hate when we leave them out on certain decisions, and if you have kids you can do the same. I hope this helps, good luck!