I personally would not mind an overseas tour. It just is a harder situation when you have an SO who also has dreams and aspirations and you sort of have to give them the hard pill to swallow.
You both need to be prepared for the possibility. If you aren't, DO NOT join the Navy, or DO NOT marry this person (if you aren't already married).
Now, being prepared for the possibility can look a few different ways. Most typically, it will mean her putting a pause on those dreams and aspirations (and dealing with the fact that it is hard to just unpause most careers without seeing significant backsliding). But some people choose to separate their family for those 2.5-3 years, living apart. That can be hard on the relationship and the finances, but easier on the SO's dreams and aspirations. Don't forget to take into account children, if there is any chance you will have them before you leave the Navy. It's one thing to say that you are okay living apart from your spouse for 3 years, and another to say that you are okay living aprt from young kids for that long, and for your spouse to be okay having no one with whom to share the day-to-day realities of childrearing (and the affect
that can have on dreams and aspirations). It's easy to just think you will cross that bridge if and when you come to it. That's a massive mistake. It's also easy to think that you will just work it out. Also a mistake. Have specific conversations and think through these things as much as you can when it is just theoretical to really determine if it is for you. Sure, it may not happen. But it can.
And frankly, even if you don't go overseas, it can still be a pretty significant hit to dreams and aspirations. You move across country. After a few months or maybe longer, she finally finds a job that is aligned with those dreams. And then 2 years later, you get orders, and she starts over. And maybe you live in a place not conducive to those dreams. And depending on her career, there can be issues with having to get licensed in a new state before being able to practice that career. These things aren't insurmountable, but can require big sacrifices and many headaches, and also career gaps and having to constantly start over, making it hard to move up.
Again, if you both aren't ready for that, you need to really rethink either the Navy or the relationship.