In terms of moving for uni, maybe it would be possible to live away from home at a local uni, so your parents would know you're still in the area but you would have more independence, or perhaps you could apply to some unis when the time comes and, if you get in, then try to reason with your parents why going to that uni, even if it meant moving out, would be the correct choice. Plus, even if you did stay living at home for uni, you will still get some more independence.
For the fixation stuff, I've had some similar issues (more in terms of not wanting to even open the possibility of liking new things rather than disappointment that it's not reality) but, for me at least, the only way to get over it was to force myself to watch other things, maybe for you it would help if you read / watched stuff about realities you really wouldn't want to live in?
For the relationship stuff: I've never had a relationship and I'm also 17 and I also worry that I'll be alone forever but it's important to keep in mind that we're still young and you've only met a fraction of the people you'll ever meet and in adult life there'll be some many more people and opportunities.