The two of you need closure

You've avoided the subject the whole time you were here, trying to not endanger a good thing. But now that you're going to be moving out, at least for a while, you need to settle the issue. You know she wants you, that has been blatantly obvious since day one, even though she is too proper to admit it. So, here it is: do you finally act on your mutual feelings, perhaps leading to the creation of a scandalous relationship that will leave the two of you separated for long periods of time and maybe even close off opportunities due to being tied down, or do you tell her flat out that it cannot be, hurting her in the short term but perhaps saving the two of you from some serious trouble down the road and leaving you freer to decide your own fate?