What should I put under the "reason for leaving" part of my application for this situation?

So I work at Subway, I have been for about 1 year and a half. So I have great experience with it, and I'm confident I can find another Subway in the area quickly, but, the reason that I want to leave the one I'm at now is because I work with my boyfriend, who is the manager. We don't get along as coworkers now and it's hurting our relationship so I just want a new job, probably Subway still, but if I don't get hired there I will apply at other places too.



What should I put under "reason for leaving" on my application?

If any managers are out there please refer yourself as one and tell me what I should write that you would accept if you needed someone at your store.



Also, if it helps, my job is 10-15mins away depending on traffic. I could put "want (or need) a closer job" but there could be a job that is just as far if I can't find any near me. And to be honest that excuse sounds weird to me.What should I put under the "reason for leaving" part of my application for this situation?
I would just write -"seeking better opportunity" and if it comes up, say you would like to be considered for a supervisor or manager position and you didn't see that as likely at your current spot as the manager there is settled in.