thank you for posting this. I am going through the initial phases of just such a situation and it is currently driving me bonkers. (Even though I've experienced it before and should have some idea by now.)
i'm stubborn by nature, so it sort of comes naturally to me. but then when "everything is okay" and there are actual and concrete signs of mutual feelings, it's like i don't know what to do, and i get confused and conflicted.
And that's it exactly for me as well. I do like inverse's suggestion on how to act as it gives you a way to release the pressure quickly (just let them know) even if it's a bit on the gutsy side.
As far as relationships go, I only tend to make an effort when the person seems very trustworthy - this after a decision long ago about trying to focus my limited energies in situations where it can lead to some sort of relationship. It usually starts with showing the other person that I trust them and sharing some things with them. Usually I'll drop some hints that I like them and try to keep it non-obvious..
..and the above works fine until they return the favor. Once they make it clear that they are enjoying the experience (or start sharing things themselves) I immediately get frightened and confused with all kinds of scenarios popping up and the inevitable endless circular reasoning that follows.
So what to do... the first thing I do is to acknowledge that I trust the other person so that they can affect me without me running away. This starts off extremely frightening and usually gets better as time goes on. The other important bit is to see the major scenarios that I expect or fear and accept them as possible while trying to experience them. This is pretty grueling since there are many of them and they all make me uncomfortable for some reason, but it too gets better. Finally, drop the ones which don't reflect the current situation and just focus on the ones that do. This has worked for me in the past, but only when I have been able to do all three things I listed.
One more point, it is a journey and your perspective changes with each new development, so it feels like you're in a totally different place throughout. This tends to fade away once the relationship has become more stable and some of the worries go away. Then you find you can focus on the fewer (and more defined) issues at hand.
have you had any success in accepting that you're likeable and liked by someone who you really care about
Yes, although it takes some time. The 'newness' has to wear off before I can comfortable feel/believe it is happening. Until then it's some part believing and some part paranoia..
have you found any insights on what causes or triggers your own "preemptive feelings of rejection"?
It stems from not knowing how committed the other person is and fearing they will leave; this can be tempered by observing them sticking around where it becomes obvious they won't just leave.
have you found ways to at least soften a little bit the impact of such feelings...
Yes, although the relationship has to allow for you to share how you feel. Bringing up worrisome thoughts or feelings is a good way to get the other person to (in)validate whatever you are feeling and get rid of at least some of the doubt.
Hope this was somewhat helpful. For some reason I had a really hard time putting it into words