Planned marriage gone wrong

Have posted this on another sub as well but posting here to get a better perspective.

My (34F) wife and I (30M) have been planning all along to retire early, settle abroad and travel around the world. For the past 7-8 years l've pretty much worked my heart out as a founder to achieve this. As per the plan I’ve signed a deal where my startup will be acquired in the next 18 months for a really good sum and transition is under process.

I've been extremely excited since l'll have very comfortable finances to spend every month and my wife and I have been deciding which country to settle in. All this changed 5 months back when my wife met a couple of college friends, changed her mind in some way and has since then decided to apply for a PhD in Bangalore.

This pretty much locks us in India for at least another 4/5 years and wasn't part of the plan at all. Since this happened we've been arguing about it every single day for few months and finally decide to separate 2 weeks ago.

I've learnt a hard lesson that any amount of planning ahead in your marriage doesn't guarantee a great life ahead. 6 years of relationship and 3.5 years of marriage has ended this way, and now I'm in a position where I'll have to completely start over on the personal front. I might have money but nothing else at all since the company deal is already through. Neither am I keen on taking up an employment.

I’m still unable to fathom, what might have caused her to take a U turn and that too, quite suddenly? She was really onboard with the plan of retiring early and had taken on a chill job she could leave anytime, and was more enthusiastic than me in deciding on the country, planning retirement and stuff.