So, about the constellation as such: yes, it is basically possible with only one income. It was the same for us. Husband working shifts, net income like yours, also thanks to tax class 3. Plus extra income from holidays, Christmas bonuses, vacation pay, one-time payments, which are not included here (and shouldn’t be). I was fully retired back then with 150 euros full EU pension. So more like pocket money. We had 7,000 euros in equity, which was enough for the additional purchase costs. Thus, it was a 100% financing, total volume 210,000 euros (139,000 for the house, 10k for "Modernisierung" and 60k KFW renovation loan). The 149,000 for the house were also split again into 50k KFW home ownership program and 99k normal bank loan, mixed interest rate fixed for 5 years ("are you crazy??") 2.5%. I’m mentioning this because I don’t know to what extent the composition of the components influences the banks’ loan approval (different evaluation criteria?).
That was in 2012. After 5 years, we already did the first follow-up financing because the fixed interest period expired and radically changed everything. We terminated both KFW loans (due to bad interest rates) and consolidated everything into a new loan at another bank at 1.4% fixed for 10 years. Total volume 180,000 and the house value meanwhile had risen from 139,000 (initial valuation) to 235,000 (valuation by the new bank). Loan-to-value therefore only just about 77%. In 2017 we still had the same constellation single earner/pensioner, but this time with tightened mortgage credit guidelines. It still just worked out (under the new guidelines, kids are simply assumed even if there are none and none are planned, and you have to be done with the loan by retirement – haha, for me). We agreed on 3.25% repayment back then and it worked out mathematically (the rate was 697, meanwhile we increased repayment to 3.75% because I am working now).
For you, the rate is a bit higher, but the interest rates have gotten lower, plus the credit guidelines have been relaxed again. It may balance out. However, we had no ongoing loans back then. Or is your car paid for in cash? Unfortunately, I can’t recall right now.