I have addressed this issue several time via personal messages. But being that I have seen it in so many places, I think i will make it a bit more public.

I have been asked and have seen asked “I am thinking about starting HRT. But my BF, GF, Wife, or Husband does not want me to get the surgery.” Look you are in a partnership it is no longer about just you. Sad to say but this is the truth of it all. HRT is a very very selfish thing to go through it is all about you and no one else at least a lot of people think that way. I am sorry after spending a year on the HRT i have started to look at the idea of Transitioning in a new light (cue game show music here). Look while I will say that HRT is about me, it really is not just about me.
I have been trans all my life, I told my ex-to-be wife in 2006. That was one hell of a bomb dropped in her lap and caused a few issues. She over the years did not handle it well. When i told my sisters, they turned out to be Transphobic. They made a few bad choices as in outing me to others without my permission. They told my Oldest Daughter in the US. BY doing this they destroyed my chance of telling her in a kind gentle way that could have eased the impact. Then they told my parents who at the time were fighting Cancer (both of them at the same time). My parents did not take it very well. I did find a sort of a middle ground with my mum but she passed away a year after and we lost a lot of time. I will not forget them doing that, in fact I refuse to talk to both of them now. My dad, well I am not really sure what he thinks as he does not do emotional things. But if you look at what I lost in this area I do not see that it has caused a big hole in my heart. Cause no one needs bigots. Though I would have loved to been able to talk it all over with my mum before she passed. I hope my dad can find it in his heart to ask as well. Though I count myself lucky my dad might be trying he is talking to me and calling me Al. That works okay for us to have that ground.
My friends are still going through the Transition with me every day. Last night one of the best friends I have ever have had has had ( 4 H words, lol) to ask a name question. Which is very cool and I am glad he feels secure enough to ask. I did lose a few friends, though saying that were they really friends or just people passing through.
Now if you are in a relationship you need to come to terms with the fact that it might not survive. This is going to rock your world people will come and go, your health is going to change, your body is going to change and sometimes that change does not work for the other party. I have a friend who her partner is Trans and it survived. Though I am sure 100% it was not easy on her.
This is also going to impact with you on an economical level. You might lose your employment or you might not be able to find some. You might lose the amount of money you are used to. You will end the male privilege to life and that means less money.
You (if you pass) will have to get used to women privilege as well. Men opening doors, letting you go first, saying nice things about you, and men being a bit cheeky.
You are going to have to remember that it is easier to get flies with honey than vinegar. The fact that you are wanting to be a woman means a huge change in the way we ask and need help. You will find that if you are kinder you will get more.
I am going to point out that if you want to know what you might go through read my timeline and remember that it is mine not everyone is going to have the same issues.

Here is something that you need to know that the world around is going to change. I gave up on a few people and things that once I counted as rock solid cause of the issue of becoming me. I found a few people and things that I wished were in my life always but sadly were not there.