So I've been working in a toxic work environment for just over a year. My boss passively bullied me by marginalising me in front of others. He comments on my work via another colleague and won't want to give me any attention. But I managed to do my job well enough that the customer is very happy with my performance. So he couldn't openly do anything to me.
A couple of months ago, I started helping on another area which is managed by a different director (under boss's consent). I did well enough that that director offered me to move across. This role is an internal facing role, unlike my current customer facing role, and it's a fixed term role lasting for just over a year. I do like what I was doing and enjoyed a good relationship with their team. So I accepted and it will be announced soon.
In the meantime, there's a very high profile project just launching and I'm in the middle of it with my current role. I really enjoy it from technical perspective and I need to work with a much wider portfolio of people across the group (so not so much restrictly with the toxic branch). It's also for the same customer who named me to get involved.
This project will last for a few years. Because I'm moving, there will be another person coming in with a higher title to replace me. The chance, in a year's time, is that I might move back and report to this person once the fix term role ends.
I now struggle to think of an excuse to explain my change of team/role without harming my future. I don't want my customer feel I'm moving because I don't want to work with them and their project. I don't want the wider portfolio of people I started working with think the same. (People around me though probably won't be surprised as previously any person in my role never lasted more than a year). I don't know how to explain to those who matter, so that I leave the bridge intact there in case I want to move back.
The truth is, the only reason I'm moving is my boss and his team. But I can't say that to anyone.
Any suggestions please?