Intentionality bias.

The built-in tendency of the human brain to make everything about YOU (which it never is), instead of treating it as a drive-by incident (which it ALWAYS is). This is a universal cognitive bug in our species' software. It helps to question one's instinctive emotional reactions, especially in situations like that.

Drinking makes this bias worse, which is why you often see drunk people arrested for violence.

Is this person sick or stressed often? Do you normally spend an adequate time with each other doing a variety of bonding type things (ie-you aren't just having sex)? What ways does it qualify as an awesome relationship? These are questions that need some filling in if you want a serious opinion.

Being insecure with oneself, is very common in young people. Relax a little and enjoy your life.

You just eloquently described the issue (BTW that sort of behaviour would make me run as well - it IS due to insecurity). And you're able to recognize and take ownership of the problem which is arguably the hardest part of stopping unwanted behaviour. As long as you catch these feelings when they arise, take a breath and act accordingly (cut them a break), then all will be good.

Same. Except the worst part about it in my situation is that they don't want to and it actually IS because of my behaviour... don't let it get to that point in your relationship.

how is communication in your relationship? if you feel that your sexual needs and desires are not being met, are you able to discuss that with your partner is a calm manner, and not before or after intimacy? i am asking because oftentimes intimacy avoidance could be an indication of a problem or an issue, and you maybe intuitively right that something is indeed wrong, but not sure what it is. sit down to talk with your partner, calmly tell them how their actions made you feel, and find out what it is. open and honest communication is the key to a successful relationship.

I suppose I should put this more bluntly.

My memories of being insecure and unsettled in situations like this, are quite vivid. Telling someone to relax and be more secure, is almost certain to make it worse - one would then feel unsettled and insecure about feeling unsettled and insecure, and it just feeds on itself. No amount of communication or togetherness is going to fix this, and the more you try to avoid thinking about it, the more painful it will get. DON'T DO THAT.

Your focus belongs outside yourself, on the other person. Do they need space, or nurturing, or just for you to pretend that things are normal? That takes your mind off your anxieties, and puts it where it may actually be some use: your partner. DO THAT.

The idea comes from the only definition of love that ever made sense to me:
When I love someone, their happiness and well-being is at least as important to me as my own, if not more so.

It has the advantage of clarity, and I can easily sort out whether I truly love that person. This has nothing to do with being in love, a different topic altogether. Attending to the needs of someone other than yourself, is a very direct expression of love, romantic or otherwise.