I'm a manufacturing engineer specialized in machining exotic alloys and complex parts, even though I have changed career a few years ago I have experience in manufacturing complex military parts.
So I would probably be in a factory trying to produce as much military equipment as possible.
I believe you can flash klipper on the Prusa printers, they even have an official page on how to flash custom firmware and it does not break their warranty.
As others have said, there is no right answer but here are my thoughts based on my experience.
Mortgage
The apartment is under your name so I would expect you to pay the mortgage.
One thing you could do is that your girlfriend puts a share of the mortgage cost into a savings account under her name. It could be the equivalent of what she's paying now for her rent of the equivalent of your mortgage minus 30%.
This way if you stay together and decide to buy a new home you can both contribute to it with a nice down payment and if you split up you both get your marbles back.
It also levels your salaries and you are contributing equally to the housing cost so there is no resentment being built on your side.
Utilities and groceries
What I did with my girlfriend (now wife) is that we were doing a pro rata monthly contribution to a bank account that was used for everyday life. In your case you are earning 30% more then you can contribute 30% more to this account. Then everything like electricity, groceries, restaurants together ... Was deducted from this account.
It's quite easy to get a free bank account with two cards so we used that (we used N26 at the time but there are plenty of options, the bank account was technically a single person account with two cards but it did not really matter since we were not keeping a lot of money in it). We started by keeping track of all our expenses on an app like Tricount and regularly balancing our contribution, it's easy to set up but it requires to keep track of all our expenses and was quite annoying to do on the long term.
Agreed, Native American food is extremely diverse. Knowing that the continent was as populous as Europe on a much wider range of climate I suspect the food was way more diverse than Europe at the same period.
Also, Mexican food is not just Native American food, it's a creolization of Spanish and Mesoamerican cuisine.
My point was just to say that native American cuisine deeply influenced the way we are eating today.
I'm replacing an oil boiler with a masonry stove. There is something about having a fire in a home that makes it so much more comfortable compared to a central heating system.
This is also what Europe needs. Europe needs to seriously increase their domestic military manufacturing capabilities now that the US has proven they can't be trusted.
If this money is invested in European military industries then they will need to considerably ramp up their production and overall it will strengthen European military power.
I discovered creamer recently, I honestly don't get it. It tastes awful and why not use actual cream or milk in coffee than this thing ?