The third life hack has to do with relationships. It is very simple: to be the best partner you can be for someone else, work on your own self first. If you are happier, healthier, and better at what you do, then you will be more attractive and generous to someone else. Don't worry so much about filling a gap or need in the other person's life: that is mostly their own job. Also, don't worry about whether the other person can fill gaps in your own life. Treat the relationship itself as though it were in the tier 1, with some tier 2 things mixed in. The relationship is not there for some other end, but is an end in itself.
If the partner doesn't want you to be better at what you love doing, then that is bad. So if a partner thinks you shouldn't be taking piano lessons or going back to school, that is a big warning sign. By the same token, you shouldn't be threatened by talents your partner has, even if it makes you feel inferior. The more tier 1 things your partner has, the better.