Ultimately, if you are talking to a lawyer and trying to get out of your commitment, you do need to make a compelling argument (in the legal sense of the word).
I didn't ask you to justify your position because, from my standpoint, there really isn't adequate justification. Your reasons are irrelevant to me. Despite that, I was actually trying to help.
You seem really fixated on things that are irrelevant to nearly every military physician and it suggests to me that you have a very inaccurate perception of military medicine. Although, once you declare yourself someone who wants to bail, expect that you will receive way more of the business end of the .mil stick than I ever will.
The reason that fellowship, in part, is based on service is that we need generalists. So, they hold fellowship as a carrot to encourage people to complete a generalist tour within their specialty. This isn't about saying Hooaa (or whatever your Army types say), its about seeing patients. When you accepted residency, they didn't guarantee fellowship and, if you had asked, everyone would have told you that it probably wasn't going to happen up front.
I suspect that your perception (bias) of what life in mil med is like has created a great deal of anxiety for your fiance. If you go in expecting to hate every minute, your spouse will have to deal with all that negativity. Bad for a marriage and for your sanity.
If you want to reveal your specialty, we could talk in more specifics about it. But, get over the military stuff. There are great doctors at every MTF with haircuts that have never been within regs, etc. If that stuff doesn't matter to you, you can just ignore 99% of it.
There is a huge difference between talking to a lawyer and letting that lawyer get involved on your behalf. The former is a totally reasonable waste of money. The latter is a bad idea.