Not telling is not necessarily lying not to tell the person you are having a relationship with that you are transgender. However, what you tell the person you are in a relationship depend upon how old you are and what stage you are in your life cycle. The question of your ability to bring children into the world, may well become an issue and then you will have to tell your partner you are infertile, unless you had your sperm or eggs put in fertility banks, which will again take some explaining.
Since I am in my sixties and in a partnership with another person while we raise our 10 year old son and am not into casual relationships, for myself, I accept that no matter how I change my body to appear more effeminate, for many who know me I will be a transgender lady. To acquaintances who see me as a lady, I don't feel that I have to out myself. Others whom I live with will do that.
But I am what I am, a lady. I am not what others think I am. But, this is just the world I live in and I helped create. I am responsible for my choice, which to my code of honor is not a choice, to stay in the relationships I involved myself in until they come to their natural end. Relationships are not all sunshine and lollypops, but have all of the elements that those whom climb Mt. Everest experience.
I have never, climbed Mt. Everest, but in my later years I walked out of Canyon de Chelly, with much shortness of breath and achy muscles. And I spent much of my working life in front of many different classrooms of children, so I have a rough idea. Raising ten children with two different spouses has many of the aspects that climbers of Mt. Everest must experience.
What I think is that you do not have to explain to everyone you have a relationship with that you are transgender, but it is important to know how they feel about being involved with transgender individuals emotionally. This is only for you to look out for yourself emotionally. Why put yourself in the same position of fear of exposure you had when you were first dealing with being transgender and were afraid of how those you had relationships with would feel about you?
Of course people in relationships don't tell each other everything about their pasts, but if they really love each other, if they find things out they don't like about each other, they will be able to forgive and forget. How would feel if you found out your spouse was a wanted felon and hid it from you for 20 years, and they it became public and they were arrested?
Now being transgender is in no way comparable to being a wanted felon, but some people feel that strongly about it, however wrong that is.
One of my blessings in being transgender and growing up in an alcoholic family is that I have become more tolerant of other people's short comings and temperments, sometimes too much so. My response to finding out some one I was having a relationship is was a wanted felon, I would probably think, "So, what else is new. It's pare for the course."
There is no one right answer for anyone and many people are becoming more accepting these day. At least they don't immediately stone you to death when they find out you are transgender. I get a lot of so what's, even from the police, your life style is your choice. But I have found that living in Florida as a senior age grandma, that older people for the most part are just invisible.
Each individual has to decide for themselves when it is important for them to out themselves as transgender, if they are not already out. There is not right or wrong answer. There is either some degree of happiness or some degree of sadness and grieve. And one is stuck with accepting whatever outcome happens.
Everybody else lives in a world
