You can and do have relationships with everything in your life. Not just your friends, or your family, or your pets, or your phone. You have relationships with parts of yourself, your job, your beliefs, as manifested by "self talk," the conversations you have that nobody else hears.
What does it mean to have a relationship?
A relationship is an exchange of energy and information. It is a living process, meaning that it is born, grows, lives as long as there is a continued exchange, and eventually dies once it no longer meshes with the ecosystem of relationships in which it lives.
You have relationships inside you. Those relationships affect your relationships to people around you. Relationships with others affect your relationships with yourself.
All life satisfaction and dissatisfaction is the result of the quality of your relationships at the moment.
Relationships increase our life satisfaction, make us feel more alive, when they move toward balance and equal exchange (of energy and/or information). They make us less happy (less fully alive) when they move away from balance and move toward lopsidedness.
When you tell your friend a secret, and they tell you one of theirs, you feel more satisfied with life, filled with more aliveness, because you actually are more alive. You have strengthened ties to another living being. This makes you...more...alive.
When you feel threatened (and I like the SCARF model of psychological threat), it is the result of moving toward imbalance in a relationship. A friend who listens to your secret and doesn't share anything like that with you, and perhaps they threaten to tell someone else about it if you don't give them your new shoes. An imbalance makes a relationships less sustainable, and the threat of losing relationships makes us feel less alive.
Relationships with parts of ourselves are tricky, but they work the same way. Inner voices talk to each other, or talk to you about each other. Even though it all might seem like it's "you" or "I" in there, you're really a "we," just like me, and everyone you know.
The part of us that wants to be ultra-successful has a relationship to the part that wants to just enjoy life as it is without having to put conditions of achievement on our perceived happiness. Those two parts can be at odds, or they can have a balanced relationship. At odds, they fight over who gets to control our energy, and both will lose, as will we. That's lose-lose(-lose). In a good relationship, they take turns being in charge of our energy, and they don't hog the wheel for too long before allowing the other to steer. Then we get to enjoy life both now and later. Win, and win.
We can use this framework of "everything is a relationship" to probe parts of our lives that we're not happy with. If you have a topic of inner turmoil on your mind, ask yourself, "What relationship is at the center of this?" Is it a relationship inside you, or with someone else?
Once you find the relevant relationship, ask yourself, "How is this relationship unbalanced?" What directions are the energy and information flowing in? Then ask, "What would it look like if it were balanced, reciprocal, smoothly flowing in both directions?" What is the tiniest step you can take to move in that direction?
Take it. It will make you more alive.