I don't think it's possible to get someone to stop ignoring you without seeming desperate. Instead, maybe you could look at it as though they are just not worth your effort or time? Easier said than done if you don't value yourself though....I once lived there in No self value street!
When you establish a good connection with someone, it's not hard work... it's a roller coaster of great emotions and they don't back off nor do you question yourself.
If it starts off bad, normally it ends bad.
Find the person who is worthy and compatible with you....it will save you a hell of a lot of self doubt