Desire for joint property - currently separated

If you want to get married before making the decision, in my view (I am a bit old-fashioned, I know), the matter is very clear. Combine money and debts and then decide, with everything being split 50/50.

Because if it starts like this, what will happen if one of you becomes unemployed? Will the other then lend him the money and demand it back later; of course with interest?

Living together and getting married also means sharing everything.

As I said, I am old-fashioned...

Would rent house if it is rentable

I can hardly assess that. Are there many who rent a single-family house? When I look at "comparable" rental properties in the area, I would actually have to ask for 1500, rather 2000 cold rent. Who is supposed to pay that?

The question is also whether your girlfriend would actually like to move into the house. Often there is a story that makes this difficult. A fresh start therefore has its own appeal. However, if she likes the house, she could simply put in half of the realistic asking price and it would belong to both of you together.

The question is also whether your girlfriend would actually like to move into the house. Often there is a story behind it that makes it difficult. A new start therefore also has its appeal. But if she likes the house, she could simply contribute half of the realistic selling price and it would belong to both of you together.

I probably expressed myself unclearly at the beginning. She has practically been living with me in the house from the very start. I moved in summer 2016. She then moved in permanently in mid-2017 after she terminated her apartment. However, I have always borne the costs for the house (loan installment) alone. We have split the additional costs and everyday living expenses fifty-fifty. Thus, no one has been disadvantaged so far.

She does not want to give me half of the realistic selling price, but half of the value at the time of her moving in. In the meantime, however, prices have risen rapidly and I have invested a lot of money in the outdoor facilities. Those would definitely have to be taken into account.

In general, it would be nice to share the burdens equally. Then I would also no longer feel guilty about avoidable consumption (new car, vacations, computer technology, etc.).

Honestly, I would advise against a marriage in this constellation. Either you do things together or it's a shared apartment. But this has already been discussed here countless times and in great detail, and there are other opinions as well. Apart from that, I consider your financial analysis, especially the savings rates, to be very unrealistic. You cover your entire living expenses with 700€/month, your girlfriend even manages it with 600€. I don't believe that.

Honestly, I would advise against marriage in this constellation.
Either you do things together or it’s a shared apartment.
But this has already been discussed here multiple times and in great detail, and there are other opinions as well.

Apart from that, I find your financial analysis, especially the savings rates, very unrealistic.
You cover your entire living expenses with 700€/month, and your girlfriend does it with 600€.
I don’t believe that.

The savings rates are actually realistic, as I have made corresponding special repayments over the last 4 years and also invested money in the house on the side. We are probably the exception. When it comes to private consumption, we are very frugal. I’ve already deducted private insurance from my net income. So I actually earn more. Tax refunds, Christmas bonuses, and reimbursements for private health insurance have also not been taken into account.