My husband and I earn roughly the same amount as the OP and his girlfriend (by the way, my husband also works in the metal industry with IG Metall collective agreement wages). We are only slightly older (29 and 27). Our house will cost about €350,000 "all inclusive" (with land, garage, outdoor facilities, etc.). That is certainly possible, but we live in the countryside far from any big city, so you probably can't compare that with prices in Kassel. What also worries me about the OP is the lack of equity or the fact that you haven't saved anything so far. For example, we bring in €90,000 equity in the form of money and additional equity through our own labor. We finance €240,000 and pay about €870 per month. That should also work once the child is here. If necessary, we can reduce the rate during the critical time and then increase it again later. However, the rate is set rather conservatively anyway, and we hope to make extra repayments regularly. But without equity, with a loan amount of about €300,000, and with your income, I also see the situation rather critically. I too would recommend, if necessary, to save up a little first, at least the ancillary costs.