Learn English – What do you call someone who chooses to stay single for life

Not necessarily a virgin, but someone that has consciously chosen to stay single for life (and is content with that decision). Hopefully, there is a single word for it. Example: Ralph Nader

UPDATE: Apparently, there isn't a word for this. So, is anyone able to make up a word for this? Criteria:

• Not in any relationship by choice
• Not interested in ever being in a relationship
• Very happy and content with that decision
• Word should ideally be unambiguous and not have other connotations

UPDATE: This word or phrase should not be a descriptor based on the lack of its opposite. It should not misdescribe the above requirements as a lack of desire for sexual intercourse. The above person may be perfectly happy having sexual intercourse but chooses to not be in a long-term relationship. You can think of it as being married to no one (which is not the same as a lack of a marriage). They very likely will not have intercourse with others. However, being married to no one does not mean that they dislike sexual contact or romance—however highly correlated they are.

A phrase is suitable if no one-word descriptor is available.

This word or phrase should not be derogatory in any way. It should not be rewording of a spinster—which is describing their relationship status as if they "struck out" or "failed to get traction" in finding a mate. People can be content and complete as singletons. This descriptor should unambiguously describe that they are content with the decision and that they chose it of their own free will (even though they could easily, and at any time, be in a relationship if they so choose). In other words, they are not single because of lack of ability. They are single because they chose to be.

If no word that describes this is currently available, feel free to make up your own word and provide its proposed dictionary definition. If you do so, please note that you are creating this word and that is your own submission.