So if the problem is that we are social animals and but other people are frustrating, how does one resolve this tension? Is it better to habituate ourselves to be alone or is it better to resign ourselves with dealing with the frustrations of other people as just the cost of being a social animal? — schopenhauer1

People are social animals because the evolutionary process has made them so.
The grouping instinct is advantageous in regards to protection and the procreation process.
If an individual lives in a safe environment and has no need of finding a mate and procreating, that individual has the option to live a solitary and comfortable life.
It becomes more comfortable with age as a result of the dilution of sex hormones.