I'm in the process of changing jobs and relocating to live with my boyfriend. We've been together for five years and lived together for two of those years, but he received a job offer he couldn't refuse two states away (and, coincidentally, in the city where his family lives). I'm not willing to relocate until I have a job in my field that I'm excited about, which we both agree is a good thing to hold out for. That isn't a problem other than the fact that that means I'm applying for jobs I currently live 200 miles from.
I know interviewers are going to ask why I'm relocating to gauge how serious I am, but saying "to be with my boyfriend," sounds so juvenile to me! We're in our late twenties and I have the misfortune of looking younger (although my age could be guessed with my education and work history) so I worry employers won't take that seriously.
I do genuinely love this city and I am looking to make some changes in my career, which I mention in my cover letters.
Am I overthinking this? How would you address this question?