Definitely a tough spot, but I think your concession is necessary. I’ll echo others that have said to consider a charity that resonates with both of you for some portion of that money if possible. My parents always gave 10% of gross away to random families instead of the church as their tithe. My grandparents always gave directly to the church.
My grandfather is 5th generation pastor and my parents run their own satellite church, so religion has been a pretty big deal in my family. Only in the last few years have my parents gotten back into it in a big way. They are the ultra conservative southern Baptist type, or at least influenced. I have been atheist since I was in middle school and started questioning the whole thing in primary school despite being in private Christian schools or home schooled most of my childhood.
These days it’s pretty awkward being around my parents / grandparents. I don’t mind going to church or praying at meals or whatever, I was raised in that environment, and it is interesting to observe for many reasons. However, more and more my family is hoping I will find my faith again but I am as far from that as ever. It’s a weird thing. If they would just do their thing and not try to influence me it would be fine. But every time it’s time to head home grandma is in tears asking me to accept Jesus. The tugging on the heart strings is killer. I get it, she doesn’t want me to go to hell, but from the context of no afterlife it’s a tough sell.
I always have planned on my parents living with me later in life since they have no savings, a mortgage, and will have less than 2k/mo in social security. Every time they are being belligerent about their political/religious beliefs it makes me question how that will work out. I will have to get a duplex or something. And what if I have kids? Do I want that influence in their life?
OP, I can’t imagine going through that with my wife. It would be extremely difficult. No so much for me accepting her beliefs, but on her always hoping I would accept hers. I would feel like I was constantly living a lie or had something to hide. As others have mentioned being in a relationship where both people have opposite priorities is hard. My last serious relationship before getting married was to a spendthrift which inevitably caused a rift that could not be overcome. My wife is not very active and that is hard to overcome. I’m sure she feels about my constant requests to do/be active as i do about my family wanting me to be religious. I try to be conscious of this, but it is difficult.
In the end - my advice is to support and protect your wife no matter what. If you need to work an extra year, do it, and have a good attitude about it. Having a wife that loves you and supports you is worth a lot. Maybe it’s my upbringing, but I would say that you are the head of household, the leader, and it’s your duty to sacrifice yourself for the good of your family. If that means working an extra year to give your wife daily fulfillment, it’s a smal price to pay. Protect her beliefs, make her feel safe and confident she is doing the right thing (even if you think that thing is unnecessary). Best of luck navigating this situation over the years. 10% of your income is a lot, but it is a small price to pay.