building sexual tension

I need to have some advice here

I used to be a shy guy with little confidence but that doesn't show very often. In conversations with women I just met I come across as a social person with enough confidence (I think)
But I am very afraid of taking it a little further because I have rarely been touched.
For example. Me and my friends have a female friend in common. She is very pretty. Every time one of my friends has to leave, he gives her a hug or a friendly kiss on the cheek or something. I would like to do that too, but I feel more for her so it makes me nervous. Usually I'll say something like " good night " and then leave. I avoid body contact even though I want it real bad.

Some people touch other people during conversations and it is natural. But even though I am very relaxed in conversations, I don't tend to touch women because it makes me feel awkward.
I'm starting to notice that this trend of avoiding body contact with that girl is evolving and I don't feel good about it.

I am in my mid twenties and a virgin because of a lack of sexual confidence. I'd like to work at it but if I'll start touching her I don't think it's gonna look natural.

I think women have a good radar for insecurities like these. The last time I saw her she just left and it seems that I fail to break this physical barrier between us. I hide in a safe zone where nothing can go wrong.
When I just met her she gave me some serious IOI's but I just didn't react out of fear.

How do I start improving at this?

Edit:

I like to guess what ppl are thinking. I've overthought about this girl so often because I had/have a crush on her.
To be honest I think she liked me on the first few days we met, and I could have kissed her succesfully.
But after turning away on so many occasions I think she knows that I am just too shy for any sexual escalation and she has lost interest as a lover because of this. We do hang out, but there seems to be a distance because I haven't reacted
I think a lot of women are looking for a guy like me, but one with the balls to build sexual tension. A leader type, more dominant in the approach.
It seems only a small difference for me but I haven't conquered that fear in years