Buy the condo now. 3 years later, buy the SFH in 4S with a 30 yr fixed mortgage.
By then, since you’ll be upside-down with your condo, walk away from the condo (let the lender foreclose). Since you have a 30 yr fixed on your SFH, the mortgage payment won’t go up on you, even if you have bad credit.
The bad credit you get from the foreclosure will affect your credit card loans & car loans. But assuming you don’t owe much on these, it won’t be too bad. The loan that you use to buy the condo is a non-recourse loan, so the lender will not be able to go after you.
All things considered, it’s a small price to pay to keep your wife happy.
Of course, the lender will be the big loser. But that’s the risk inherent in the mortgage business. Lenders understand this risk, if they lose money, they can’t blame anyone else.
