My adviser is leaving. Can I ask him to support my application for an other PhD position? A little background:

I started my PhD in August 2019 at university X. I wanted to work on project A, but after I joined PhD, my adviser asked me to work on project B. He said that if I start working on project A, he won't be able to help me in any matter. He's a very nice guy, he said that I can work on whatever the project I want. I decided to start working on project B because I don't want to get lost and have nobody to help me out. (I had a horrible experience in my MS where I worked on a project about which my MS adviser didn't have any knowledge).

For the last 4 months, I have been working on project B. It's okay, but I don't feel happy about it. It doesn't motivate me. It doesn't give those internal joy-feelings.

Current situation:

My adviser is leaving this university and moving to university Y. He has offered me three options:


Change research group and stay in university X
I stay at university X and he will supervise me from university Y (he becomes an adjoint faculty, if department chair allows)
Move out with him to university Y and start working on a new project (which is also not of my interests)


I don't want to choose option#2, for sure. Option#1 is also not quite suitable for me because no professor here is working on something that interests me (quantum machine learning). The salary that I am getting from university X is much more than the salary that I will receive from university Y. I might choose Option#3, because at least I know that this professor is a very open-minded, nice and genius guy. I have to make a decision before June 2020.

Question:

I want to apply for an other PhD position, the one which really interests me. Is it okay if I ask my current adviser to give me a recommendation letter and support my application? What reaction of him should I expect?
Your advisor has offered three options. You have a fourth. My best guess is that the advisor just forgot that fourth option rather than considered and rejected it. 

I strongly suggest that you ask him for your support in starting over at a different university. Any ethical advisor should support you. If you've been doing good work, they should support you strongly. 

In your request, though, I'd do two things. The first is to talk about the research trajectory that you would like to get on and suggest a few places (and even professors) where it would be possible. The second is to ask, also, for his suggestions about places to pursue your goals. He may well have contacts that can be useful to you in changing. Try to make your change a cooperative endeavor with the professor, not a break. The future may hold collaborative opportunities if you work it right.