It certainly changes a relationship. If it's changed for the worse or the better depends on so many factors, the biggest probably being how you as a couple communicate. That and respect for the other person as an individual. The pressure can make a relationship break or form a diamond.
Here's my very individual look from a CALS perspective.
I at times found it hard to keep a romantic relationship with my boyfriend. He made it easy as he was super-sweet and caring. What made it hard for me was the sheer emotional, mental and physical load that caregiving is, with some added advance-grief to send me over the edge at times. I sometimes saw being a CALS as my job, because no single other person was remotely as involved in every aspect of not just caregiving but also of household, financials, coordinating friends and worrying about the near future.
So I was on the job all the time (in the beginning trying to focus on my paycheck job at the same time).
"Being on the job" means go-mode, not much time to dally, it's just another mindset as spending some quality time with your spouse. But there is no clock on that "job", ALS never stops, you can never be to quick to get the next needed equipment ready, be informed about what might be ahead, read through information and stories to help your PALS make informed decisions. So even if a PALS is as relatively easy-peasy as mine to have his needs taken care of, there is the constant mental load.
I early on worried about turning from a girlfriend into a full-blown caregiver as that would also mean turning my PALS into a mere patient and losing a boyfriend at the same time. He felt the same way and he sometimes had to deal with the verbal consequences of having a girlfriend as opposed to a professional caregiver. ;- )
Couples bicker, couples get into an argument, couples make up. Compared to the 15 years before there was less bickering, very few arguments and more heartfelt meltdowns and deep talks.
I didn't wrap him up in a secure, soft ball of cotton, trying everything to keep the harsh reality away from him. While the muscles set down their work, his brain was sharp and he stayed mentally stable. It was clear that I was taking over more and more of his movements but he could help hugely with what he was able to do. Often that "just" entailed being charming, patient and empathic with me (he did great in that regard) and others (where he'd lose patience sometimes). He always was my confidant and someone who helped me to deal with stress or life in general. And I hope he told me all his grievances in return.
If a PALS has the fortitude to know that (s)he's not the stressor but the reason the spouse stays around although there's all this stress of ALS involved, that might help understanding. I could complain to my boyfriend about difficult healthcare workers, being so freaking tired right now or just about some silly everyday life, because he knew that I was there by choice. A partner's job is to sometimes see the worst of the other person and comfort them nonetheless. I still felt bittersweet about losing him while having the great priviledge to be comforted in that grief by him.
Frustration alone is not the problem, it's using the only person around to vent that frustration and making it hurt, too.
Caregiving can get very lonely at times, too. The burnout list of KarstBoy is very real.
My advice to CALS always is to get as many people and their help involved as early as possible. Being a silent hero will break you. Taking friends and family along for the ride is work, too, but it pays out. If I had the choice of cleaning or writing an update to friends I would always choose the latter. And if I had luck of having a professional caregiver in the house I happily handed over the duties of getting him ready for bed. I knew that my PALS most of the time would have preferred me over a professional and I'm thankful that he tolerated them for me. After a long day my patience for the upteenth toilet transfer or mask adjustment could be limited, so I enjoyed resting up for a bit before gliding in at the end of the routine. I was not only making sure he was comfortable and the caregiver had understood everything correctly but I also came to cuddle and talk, kiss him good night and maybe listen to an audio book together.
I'm sorry for this rambling post. It's just something that really kept my mind busy at times. rmt kinda said it all in a couple of lines.
I hope your wife finds help and support. The feeling of being caught in this situation without escape or relief can stand in the sightline of how good you were and could be as a couple. And I hope she treats you as well as can be, as you deserve respect, love and a partner on eye-level.
