Hi Jayne,
I just joined Susan's today, though my wife (she's MTF) and I have been transitioning since late 2010. For context, prior to her transition, I identified as a straight woman and we had been together for 6 years, married for 4. This year it'll be 10 years since we've been married. I can't say that it hasn't been a challenging road for us as a couple, but I will say that our love for each other has been what has made us work hard to figure it out.
You asked about what SO's may have tried, and I think therapy (both my own individual and couples therapy) has been incredibly helpful to both of us. We each have our own viewpoint on what is happening and it's important that we share that perspective and attempt to understand each other. Part of my joining this forum is exactly for that, to better understand her, even though it's been over 5 years since we've been transitioning.
You may have noticed I say "we". Initially, I saw her transition as something she was going through, but over time I've realized that it's not only her who is transitioning but us as a couple as well (and our friends, and family and co-workers, etc). It was scary at first because it made me consider my own gender identity and sexuality, and even now, I still do. But, I recognize that this is all a process, and it takes time, but it's a process that I want to see through because I love her and I still want to live the rest of my life with her.
I can say, from my own experience, when we first discussed her transition, it was a bit of a shock, but I was always supportive from the beginning. I've found that it doesn't seem to be very common (or maybe it is, which is why I'm here to find others like me) and people that we have told have generally responded with what feels a little like pity...which really bothers me, but I get it. Not everyone stays with their spouse, and it always seems surprising to people that I did.
However, over time, we've gone through all the different stages of transition; clothing, HRT, make up, electrolysis, laser, awkward androgynous stage, name change, and now we're finally in Argentina getting ready for her FFS with Dr. DiMaggio (1 week away, woo!).
We've had our ups and downs, and we've cried and fought and hugged, etc. but we never let go of what matters most, which is the LOVE we have for each other. I never thought I would end up married to a MTF trans woman, and now I'm considered a lesbian by most people because she passes as female. But, I don't care, those labels don't define me or us, and I've finally gotten to the point that if someone I know has a problem with me or my wife being who we are, those people don't deserve to be in my life, whether they're family or friends. I get to choose who I let into my life and I won't choose people who make either of us feel bad about the choices either of us have made in our lives.
All I can say, is that it's a process and it takes time to get used to the changes, but if you can roll with the punches and learn to enjoy every chapter of the process AND acknowledge that it's a transition for BOTH of you, I think you'll find that a lot of things you're worried about today, won't even matter in a few years.
I hope this was helpful and good luck to you and your wife.
hugs