Not really, but I don't really have much of a choice in the matter. The best I can do is model for my children that I love my wife despite what she is going through and of course show them lots of affection.
I read through the OP and the rest of your replies but this was the one that made me want to post.
I genuinely think you're doing the right thing overall in trying to be supportive but I'm going to push back against this point because, in my personal experience, this is not the lesson that kids take away from a situation like this. I can say this because of my own experiences being the child in this situation.
My parents married relatively late in an arranged marriage. Like you, my father had had girlfriends/relationships before the wedding where my Mom had not. After she gave birth to me, my Mom fell into a depression of her own. She cared for me (and still does as far as I can tell) but, as I grew older, her depression meant that she couldn't show her love to me in the way that she needed to. Once I grew old enough to not just be a receptacle for any affection she had to spare but also to have my own opinions and start questioning things, I started seeing the other side of things.
My mother would frequently ask my father for things and he would always give her what she asked. He bought plants, household goods, cars...you name it, she got it. For a time, they were enough but soon they became only another point of argument or, more frequently, something else to be ignored. I'm now 35 years old and my parents house is full of just..."stuff" and almost all of it is my Mom's. Multiple appliances and gadgets (so many that 2/3s of a 3 car garage is full of it), all manner of leftover goods from the things that were purchased at her request. None of these things made her happier. When she wasn't going through "stuff", she'd look to me to fulfill her in some way. What started as love became an obsession. I was constantly compared to other kids academically and physically, told I needed to lose weight while also being fed way too much because I was a "growing boy".
Steadily, this turned into more frequent and random abuse. On one occasion a Quiznos worker got my sandwich order slightly wrong (my mom weighed the sandwiches and found out that the weight of them was a bit less than normal) and when I told my mom that I didn't care, that spiraled into a two day session of being called a coward and a failure. Now imagine this multiplied over everything. Changing majors in college, having a girlfriend before 18, not getting accepted to all the UC colleges, etc., etc.
My fathers response during all of this was to tell me that, because my mom was "sick" or "moody" that I needed to be the responsible one and just bear with her tantrums. She couldn't help herself so I needed to help my dad by being the grown up. This did not sit well with me and only led to me feeling like I couldn't depend on either of my parents. Years and years of this behavior have only reinforced to me that my dad enables the shit out of my mom and she is still the same mess that she has been for the last 30ish years because of it. Therapy for this stuff was never on the table because it's just not talked about/done in our culture. I ended up going over many years for myself but my mother never has.
I wanted to give you some idea of what can happen when you are too supportive. I know that you want to be supportive, that you love your wife and that you want to set a good example for your children; however, that's not necessarily what you're teaching them. You can support your wife a lot (which it looks like you've been doing) but you need to understand that unconditional love and support is not a good way to function at all times. Ultimately, if she doesn't want to be happy or know how to find it for herself, your continued support can easily lead to you enabling her depression even more. You can't "fix" other people with your love; they have to be ready and willing to fix themselves too. Do not burn yourself or your kids trying to keep someone else warm. It isn't worth it.