Is it fair to ask for them to shorten their time abroad? (22F 🇺🇸 and 22M🇺🇸->🇯🇵)

Hi all! For reference, my bf and I (both from the US) started our relationship and were together over a year irl and now he’s in Japan where he moved to do a job, so we’re now in ldr. This move wasn’t out of necessity or anything (he easily could have gotten the same job in the US) he just chose to go because he’s always loved Japanese culture and wanted to live there for the experience, etc. For a long time before he moved we had many conversations about being ldr and in these conversations I was always clear about my reluctance and how it wasn’t really something I wanted to do. But this is something that has been a a bit of dream of his and the plans to do this were something that were set in motion before we met and also started seriously dating. Since he’s been in Japan, it’s been very difficult for me emotionally (him as well but I’d say more for me…tbh I have pretty bad anxious attachment). And he’s fully aware of this and we’ve been support each other through it. The thing is— as much as I hate this, I love him so much and I want to make this work. We’ve both made promises to each other, and seriously discussed our plans for the near future including moving in together, getting engaged, etc. He’s expressed to me that a part of him regrets his decision to move to Japan and that if he were placed in the same position of whether or not to take the job offer today he wouldn’t (ie. Bc of where we’re at in our relationship etc.) But, nonetheless, here’s there now and his boss is still under the impression that he’s going to do 2yrs over there. I under this is a dream for him and I want him to pursue this but I really wish it wasn’t 2yrs. 2yrs feels so long to be dealing with a 13hr difference especially when it’s not necessary and essentially something he’s just doing for a cool experience. At the same time, I wouldn’t want to push him by asking for him to do less (say 1yr) or force him into a situation where it feels like an ultimatum. This has just been so hard for me and I feel like I’m out of control because ultimately he knows that I love him enough to wait. I feel terrible saying this but part of me thinks if I don’t provide an ultimatum and stand up for myself (i guess set a boundary?) he won’t take my feelings on it seriously and not actually consider doing 2yrs. But I feel like compromise in this situation would be nice….like I’m agreeing to work through ldr but could you do a shorter term? Especially given how serious the future commitments we’ve made to each other are (marriage, etc). How should I go about approaching this situation? Am I even valid or am I being totally unreasonable? Idk I want to move about this situation as healthy as possible so I thought getting outside perspectives might be a good point of reflection.