Hi CAPSLOCK,
I do understand Asperger's, the friend of mine (my best friend in Christchurch) that is staying with us has severe Asperger's, and another good friend of mine back in Spain has it too, although less severe in the spectrum. My friend here has lots of physical disabilities besides the Asperger's, and unfortunately he was abused as a child and teenager, so he carries his mental scars too. I am very good at picking the traits, and I personally have a soft spot for Aspies, as myself have some traits too (not diagnosed, and very, very mild, but they were more severe when I was a child and made my life difficult at school).
There is one advice that I would give you that can work sometimes, and others will put women off straight away, and that you probably have heard before. The advice is to be upfront and mention that you have Asperger's from the beginning. One of the main disadvantage for an Aspie during a date is that some of the traits are very, very similar to the body language of a person who is trying to hide something, or that has an unpredictable behaviour. And if the woman does not know about the condition, this will put her on guard, and seem "creepy". once a woman is on guard, there is very little you can do to recover your ground. As women are very, very good at picking gestures, there is virtually nothing you can do to "hide" it. If the woman knows about Asperger's she will relax, and will "forgive" the worrying gestures or hints, which will then be classified as "that goes together with his condition" instead of "this could mean the guy is planning to kill me when I am alone with him". Being upfront and honest will eliminate the women who would not be suitable anyway (you wouldn't want a romantic relationship with a woman who is prejudiced against Aspies to start with), and will give you room to stop trying to hide traits and be more of yourself with the remaining women. I know how difficult is to be upfront with something that you think could mean the end of a date. I know it is not easy, and you may discard this advice.
About being distant and holding back during a date... it is very difficult to advice you in this, because it really depends on the woman you are meeting. Some of them love the mysterious guy that do not give away almost anything others love the open and honest guy that will trust her with his secrets on the first date. Other women love to talk and talk and talk and do not mind if you haven't had the chance to talk in the whole evening. I believe the most difficult challenge is not to choose how to behave, but to behave in the way you are in a natural way. Asperger's makes you doubt yourself, as if you behaved in a completely uncensored way, people would still find your behaviour weird, so you have to try to combine the social ways you had to learn by memory (versus other people, who master these abilities by instinct) with the dating ways, which should be appropriate, but at the same time have to give a true image of who you are. You don't want to rehearse everything, because then the woman would not know you truly, just the rehearsal you've chosen to practice. In this sense, telling her about Asperger's and making sure she is informed about the condition will also give you more rope. If you are looking for a romantic relationship, and by chance the person you are with IS that person, then you want her to know who you are, the things you do, the things you like, and get to know your character.
Have you tried meeting other women with Asperger's? There are specific dating sites for this.
You say that girls usually classify you as "a good guy but no relationship material". This usually means you are acting as a friend, not a possible lover. You are treating girls like a brother, not like a partner. I think this has lots to do with your sexual problems, as it must be very hard to show a sexual interest when you yourself are apprehensive about sex. Can I ask, how much "sex" is "sex" for you and makes you feel uncomfortable? Are you ok with kissing, French kissing, touching? Is it just the sexual act that you find difficult?
On a first date anything can happen, from the woman running away screaming, to having a hot night of passion. This is where the gestures and double meanings play an important part, and where you have a disadvantage. You can't ask a woman to be direct and tell you what she wants, because part of being a woman is to be subtle, and this is not being mean, it is just another way of protecting ourselves. Even though you may have read here and there that "women know if they want to have sex with a guy they meet after just 5 minutes", that is just crap. We may feel an instant attraction sometimes, but if we actually have sex or not with that guy depends on many things... a woman's libido is like a candle: it's hot enough to burn, but it can be put off very easily. I may find a guy attractive, but the talk during the date will tell me a hundred different things that are actually not said: the way he looks at me, he moves his hands, the way he talks about other people, and treats other people... will tell me if that man is violent, if he is trustworthy, if he is affectionate, if he has a sense of humour, if he is self-confident.
This is why it is not possible to give you a recipe of how to behave in a date. I can't even do that if you were dating me! But if you were indeed dating me, telling me you have Asperger's would be a must. If you didn't tell me, I would very likely infer it myself, but I would still like you to tell me.
Also about how a date can escalate... usually body language is the hint here too. A woman who wants to have sex with you will get physically closer to you, as a show of trust. Women never get THAT close to a guy unless they are attracted to him (or, as in family, unless they trust that male completely), as getting very close to a man puts a woman in a vulnerable position. If she starts talking and smiling a lot and getting her face closer and closer to you, she may be teasing you to kiss her. If she leans to you to whisper in your ear, if she stands very close to you... all those are hints she may be sexually interested. The problem is, from then on, she will probably expect you to take the lead: you will have to risk getting a bit closer and actually kissing her. If a woman gives you all the hints, and you don't follow them on, she will believe you are not interested. And women who show interest and do not get corresponded get hurt easily, and she will be gone in no time.
I know, it is very complicated. And me being a woman does not make my advice simpler, does it? Hope it has helped a bit though. Let me know if there is anything else I can help with.
About what women expect you to do in sex, as in "touching yourself", it also depends on the woman. i don't think expecting the guy to touch himself is that common, i personally don't find it such a turn-on (I prefer to touch him myself

. Usually it is the other way around: a guy finds a woman touching herself a big, big turn-on. If you are ashamed of your sexuality, I do wholeheartedly recommend you to go to sexual therapy as soon as possible, because women do not expect the guy to be ashamed of sex, and it would be an unpleasant surprise for her, that may put her off. If something happened in your past that affected you sexually, you have to fix that, or try to find out the cause, and the possible treatment, before you try to have sex with a woman. If you try to have sex without having help first, you may fail, and then your apprehension about sex will get worse. I know that, especially for a man, it is very difficult to ask for help in this. But in this case I am 100% sure that you could benefit from specialist help.