You have standards. Person Right just hasn't come along yet. You can lower your standards, or hold fast to your values. Perfection is out there, and patience is rewarded.
There might be several reasons why you are still single. It might be you have not come across the right individual or you do not socialize to meet people.
You haven't met someone right for you. Increase your odds of meeting that person by widening your social circle and pursuing interests that involve meeting new people.
Many people are single because they have not found a person that they are compatible with and yet others may be single because they enjoy the freedom of being single.