Being dumped after disclosing is disheartening to say the least, but never telling the significant other in your serious relationship (and by serious, as was mentioned earlier, you're beyond having a few dates, and doing some kissing phase), is not fair to them (since the relationship is based to a significant extent upon hiding things from the other person). Put yourself in their shoes - would you like it if they hid things from you? With that in mind, despite the chance of the relationship ending after disclosure, that's not always the case. I know a couple of post-ops, who have been married, or were married (no they didn't divorce - he died after they had been married for around 30 years) for at least a decade. In both cases, their husbands knew or know about their transsexual past (their husbands' mindset was case of "I only know you as you are now, and don't care that you use to be transsexual, just don't constantly remind me that you were transsexual").
Regarding stealth - it's probably impossible to be 100% stealth due to the fact that with so many computerized records nowadays (legal records like name changes, birth certificate changes, etc.), it's possible for people to find out about your past if they do enough digging (which has become a very commonly done thing within the past 10 plus years or so, for most prospective new employee hires in the workplace). I understand, and that's just the way it is. Despite that, you can still mainly be stealth in your life - just don't make a habit of telling every Tom, Dick, and Harriet that "hey I used to be a transsexual."
Unless you have problems passing, the vast majority of people IMO, will not figure out that you used to be transsexual. I had this hammered home to me in the summer of 2000, before I went full time (which was in Dec. 2000). In early 2000, my boss (to whom I had disclosed that I was transitioning in 1999 [I'm grateful that he provided support to me - he kept me from being fired when upper management was told in a meeting about my transition]) told me the "everybody knows about you transitioning," so when my female coworkers, asked to see me dressed up in more than tees and jeans, I took a vacation day in the summer of 2000, and went back to work, to visit with my female coworkers wearing a skirt and sandals. Instead of calling ahead, and asking them to meet me in the parking lot, like an idiot I walked in the building to the department I worked in to see my female coworkers, passing all sorts of people in the process, and creating a major ruckus!!! It turned out that my boss was not 100% correct - not everybody in the facility (despite me having contact as a part of my job with a huge percentage of the people who worked there), knew I was transitioning (probably less than half the people knew that I was doing so). So they were surprised (shocked in some cases) to say the least to see me walking around wearing a skirt and sandals. Upper management was not amused to say the least. Unlike some people I knew, I didn't do a lot of don'ts during my transition, but that was one of them, and I still occasionally cringe when I think about it. My point - don't assume that everybody knows you used to be a transsexual, that probably isn't the case (unless you have a hard time passing, and are oftentimes clocked), so it isn't necessary to disclose to everybody that you "used to be transsexual" - it makes life a lot easier IMO.
