I am in the shortlist for a postdoc at a great place and I highly admire my future mentor. He will try to argue for my application in front of the hiring committee in a few days.
The only concern I have is that this postdoc position is for 3 years. I have a girlfriend in another country and she cannot come with me where the postdoc will be. My long term plan was to spend 1 or 2 years as a postdoc, then some years in industry near my girlfriend and then the two of us to go back in my country, where I can easily find a permanent tenure-track position. I want to be honest with my future mentor and communicate the situation with him without losing the opportunity (the other potential offers I could have are way worse). In any case, I want to keep my good relation with the mentor. I see two main options:
Communicating the situation with the mentor right now. The risk is that it may look that I am not motivated enough and this could lead to me not getting an offer at all.
Share this with the mentor after an offer and 1 or 2 years spent at the postdoc place. Then, I will first have higher chances to get the position and second - if the mentor understands me, I will keep the good relation with him and he can even recommend me for another academic position where my girlfriend is (that could be even better, but I don't know whether it's possible given that I will still have 1 year of my current postdoc contract).
Which option would you choose at my place?
[Remark: Having a family is a priority for me. I am already 33 years old and I am afraid that if I lose my girlfriend, I will end up being single forever, as many people choosing the academia career track.]