Was this asking too much of her, opening up like this, so she can understand your feelings?
So I decided to open up!
Me: It's really good laying with you like this. I feel quite close to you. And I enjoyed going on the picnic today with you.
Nice gentle intro there... .so far... .
I'm getting the feeling that you are open to make love, but I'm not sure about that. You've said before that after a period apart (it's been 2 weeks), you often have sex because you feel you "should", but then feel bad after because you feel you are "selling yourself out". I guess I don't think we've really been that close today - so I wonder whether this is that situation.
... .but unfortunately this wasn't really talking about your feelings or what you wanted. From what you'd said, you were tired, and perhaps fearful... .
... .but what you did here was tell her what you thought she was feeling, or what you expected her to do, which is pretty invalidating. (Note: Being told what I'm feeling was one thing that always pissed me off, even if my wife was right, and especially if she was wrong!)
Note all the "You" statements in that and how few "I" statements there were.
So I'm not surprised it all went downhill from there.
If you had a re-do on this evening, what might you have said instead?