This list is how I am, not how he is. So take it with a pinch of salt.
(1) Backing off means you're not interested, in doubt, or bored of me, causing a reason to fear that you'll leave. I wouldn't tell you about this because it is the same as not trusting you and I feel as if not trusting you is immoral/not appropriate behaviour in a relationship. My mother nailed "relationship is all about trust" into my head, and my values are to be honest at all times. So I've created my own little loophole when it comes to lying, that not saying what I feel is not the same as lying. If you were to ask "do you not trust me?" then you would provoke me to lie about it, which makes me feel bad about lying to you. I mean, this is not the same as being unfaithful; if a girl ever kissed me on the lips while I was in a relationship, I would have to call my girlfriend up on the phone immediately and go "Honey! This girl just jumped me, I'm coming home!" At least that's how honest I am about it because I would be TERRIFIED that it would come back and bite me in the ass later.
(2) If you opened up first, then sure, I would somewhat be able to open up, but I would still hold my true feelings inside because they feel as if too intense. It is ultimately confusing. I know deep inside that I "feel" way too much, but I'm reluctant to talk about it because my feelings seems to be... inappropriate. I do think way too much about myself, in a negative way, but in order for me to do so I have to practice "Everyone has experienced something dramatic in their lifes, I'm not special," and that's why I will never share the true power of my feelings. I can let a little bit out, but not its true form. For instance, feeling love; I feel love very, very intensely-- too intensely, and too prematurely in fact. I would also not want to talk about it because I don't want to seem like I'm whining about it, and if I first start to talk about it, I'll whine. Yap yap yap, continuesly. So I prefer not to say anything. Back in the days it could make me explode at one point (if you two cannot communicate with eachother well, then you'll have to watch out for that).
(3) I feel worthless if rejected (I feel like a loser, as if there is no reason to continue or move on. I will rather ignore it, and let it be). I don't like peptalks (I don't know why. The "you'll do better next time! *smile and pat on the back*," annoys me). I won't talk about it (because there's nothing to talk about). I want to feel loved and appreciated (I won't say it, because it seems girly, and I'm a "manly man").
(4) If I want space, I will find myself an activity and go at it. And I would respond questions with "in a while," or "later" quite often.
(5) Say stuff like "you know it's ok if," and "because it's only natural" and "I do too" when you want to fish something out of me. (I think)
And all of this varies with me of course. I just happened to grab this from the top of my head. Didn't polish it. Number four and five are just.. I don't know about them at all.
If he can relate to what I said above, then sure, you two need to talk more; communicate in the right sort of way.