I disagree that you need love to stay sane.
I think so because I am sane, and I doubt that I love anything. There are some other reasons.
- I haven't found any evidence that loving others is essential to stay mentally healthy
- I have reasons to think that you need to satisfy only few of our needs to be happy, and love isn't one of them (read about theory of flow, or book "Flow" by Mihaly Csikszentmihalyi)
Moreover I have reasons to believe that people who are in love are insane.
Whole concept of being in love (depending on others to stay happy) is irrational and unhealthy. Just like alcoholics or smokers, people who need love are degenerated: they are addicted to subject of love. Superior people can question social norms that say you what kind of addictions are "normal" and what kinds are not - they realize that all forms are addictions are for normalfags.
Superior people know that they need only to satisfy their physiological needs, and need of safety - everything else is optional. Trying to satisfy other needs leads (in long term) to greed, sadness, suffering. Normalfags don't bother about learning other ways of living so they believe that they need love, while superior people know at least basics of other philosophies.
There is a gap between übermensch and normalfags, just as there is a gap between spider and a fly.
If you need love, then you're a degenerated addict; read about stoicism/Buddhism.