Our spouses are both very supportive; the issue is the simple practicality of picking up and moving to a new city. We're not kids just out of college who can pile into a cheap apartment and live on ramen; moving costs alone would probably eat up half our stipend.
Yes you can! I have a well paid job in the UK and I am applying for YC et al. I would jump at the chance to go on any of these opportunities... and I would embrace the ramen!
You're not moving permanently. Get a flight to SF, and live in the cheap appartment. You're not moving all your furniture. You just have to be able to cover 3 months of rent/mortgage at your home and hope the OH can do without you for a short while.