Life, as they say, is give and take. You put things in and you take things out. The same is true for relationships where a balance of give and take is a sound recipe for long-term satisfaction.
Give and take is basically an investment, or 'bucket', system. Sometimes we put things into the bucket and sometimes we take things out. And by and large, the bucket is on average partially full. The classic example is a bank account, where we save for the future and take money out for important purchases. Slightly more complex is our career, where we invest in study and hard work and reap the rewards of pay, promotion and personal fulfillment.
Some systems are always positive, for example the money in your wallet. When it runs out, it cannot be less than zero. Yet if you borrow money, your net wealth can go negative, for example when you owe money to the bank. Debt is a source of much woe, often caused by short-term motivations, which makes it a notable persuasive lever.