- What do you plan to spend once retired?
=> I don't really get this question, it seems that this is kind of arbitrary. I am guessing 100k per year (assuming our house is paid off) would be more than enough. How do you all calculate this answer?
The standard approach is develop a contented cost-efficient lifestyle while working, then assume your expense in retirement will be the same.
Modify this by known variances. For example, if your mortgage will be paid off next year, that's a known variance. If you plan to take up sailing, arguably that's known, but also arguably it's a money sink of unknown proportions because you haven't done it yet.
If you're about to get married, you both expect high incomes and you personally want to retire, this finance discussion with the fiancee is super important. I am FIRE with a smaller stash than you already have. If you were already comfortable living on 20k (any amount under 28k, applying the 4% rule to your stated assets) and she either fits into that budget or brings her own $,
you yourself could retire right this very second!! So whether to buy the expensive house is not the first thing to decide. The first thing to decide is whether you and your spouse want time freedom, and if so what you are willing to trade for it (smaller house, less fancy house, etc). An alternate approach is define what makes you happy, figure out the cheapest way to achieve it, add a safety margin, then work to that point. In any case, the big variable for people with high income(s) is spending decisions and insight about what makes you happy. So start from the idea that work going forward is optional, but that the tradeoff of work vs spend should be jointly agreed, and start finding the areas of agreement. Design your ideal life, starting now. And don't buy someone else's $800k prefabricated vision of your life - that's almost certain to be profitable for them but non-optimal for you.
-From my quiet cozy FIRE house where I live on about $20k net
PS. The OP says you are a 37 y.o. "costal." What is that? Costar? Coastal? Costallion? :)