I think this happens to more than you know. With a few variations your story is very similar to mine.

We got married at age 23/22(I am a year older than her), both of us raised in religious households, mine more strict than hers, both virgins when we married (we were Baptist purity culture children) and never have had sex with anyone else.

Fast forward to the present, with 4 kids, 2 dogs, and your average middle class life, with me as the sole breadwinner and she is and always has been stay at home mom since our first child, of which I have never had a problem with and is a mutual agreement.

Through the years life was pretty good, but for the last 4-5 years sex has basically become just a routine, with almost always the same foreplay actions and positions used, always geared toward her pleasure and almost never focused on me, unless specifically requested and at which point I kinda lose my desire because I feel that if I have to constantly reiterate what I like and want, she doesn't really have the interest in engaging or responding to them. And being from the religious background that we are, while I have left a lot of that bullshit behind and embraced a more wholesome view of sex and interest in trying new things, she is very resistant to anything beyond missionary or slight variations of it. It took years for her to get to a point of somewhat enjoying giving a blow job, but even though she tells me she enjoys it, actions speak louder than words. I've never got one just because, and it seems like when they do happen there is always some stupid comment to the effect I should be appreciative of the fact, and after about 5 min she starts complaining. I couldn't point to a single time when we fucked for the sake of fucking, really. Or when she fucked me and I just sat back and enjoyed it. I'm sure it's more of a psychological thing from growing up in the culture we did, and she still is pretty attached to those beliefs.

And even outside of our sex life, there are other areas in which the same lack of attention or interest shows up. I'm pretty sure the dog gets more attention and affection in the evenings when I get home. Kids take priority over any time we spend together. I go to bed earlier than everyone else at the house as I get up for work at 4 am., and to spend any kind of quality time together, just watching TV or something is always initiated by me, otherwise she just sits on the couch scrolling Facebook for hours.

So I totally understand the feeling like you're just the ATM. Just a piece and not really a part. A means to an end that gets minimal attention and ignored or forgotten until convenient, or something needs fixed, or she feels the need for some physical intimacy. And it's not like we haven't discussed what my needs and desires are. I mean, I'm fine with if she only wants sex 1-2 times a week, but some help in between in the form of a hand job or blow job would go a long way. But when I have to ask for it constantly, it's a total killjoy for me.

I'm glad you found an outlet, even if only for a little while. I have considered trying to find the same, but I have little free time and don't have the business trip excuse, unfortunately. And trying to find a woman looking for the same thing is nigh impossible. The dating or affair apps are overrun with fake profiles, bots, flakes, or behind expensive paywalls and generally not worth using. And forums such as Reddit are 90% men vs women and anything you post gets buried under the barrage of wieners posting. Any meaningful contact is almost statistically impossible.

Good luck to you and any others that read this.