Sometimes the English language stinks for getting a point across. We only have one word for love, for example. In Greek, there are six. ἀγάπη (Agápe) for a selfless love, used as for one's children or a spouse, or more commonly in Biblical texts for God to his 'children'. ἔρως (Éros) for an appreciation of beauty, or lust. φιλία (Philia) for a brotherly love between good friends. στοργή (Storge) for family relationships. (Pragma) for a deep understating achieved by a long married couple (Ludus) for shallow, playful, flirting relationships. (Mania) for a crazy obsessive love.
Most of the resources provided focused on love between a couple, so I will as well. Love is such an awful word to use. Everybody interprets it differently, so it can become very confusing. This is why using Greek helps. I will first focus on healthy relationships, then delve into what unhealthy ones may look like.
Inevitably, the goal of a long-lasting, healthy relationship should be pragma, the understanding love where two become one. Here, a distinct line between lust (eros) and pragma must be drawn. Eros may feel a lot like pragma, until it's time to make a sacrifice. Eros wants, while pragma wants to give.
Do they make you happy, or does their happiness make you joyful? Pragma is patient, kind, and selfless. It does not envy, it does not boast, it is not proud. It does not dishonor others, it is not easily angered. Pragma protects, trusts, hopes, and perseveres. Pragma never fails. THIS is what love is about, not being served, but serving! More importantly, this love in a relationship MUST be mutual. In biology, a relationship in which both organisms benefit is called mutualism. When one benefits and one is harmed, it is called parasitism. If respect is not mutual, then the relationship is parasitism.
Ludus is a flirty, playful, shallow love. This is probably how many teenage relationships start (and end). With a focus on happiness, it's like building a house on sand. As soon as any troubles come, it is at risk of falling apart. This is not to say that ludus is a bad thing. It may be bad however, if it is the focus instead of the person, or if it is mistaken for pragma. Loving love should not be confused with loving a person.
Mania is a clingy, obsessive, oppressive love. It stems from a sense of worth from being with someone else, where their self esteem is tied to a person. Like ludus, the person is normally enamored by love itself, and not the person. Mania is jealous, envious, desperate. These things cannot form a foundation for pragma; a long lasting, healthy relationship.
A parasitic, abusive relationship may be the most devastating of them all. It is not based on respect, but power and control. It mostly takes the form of one party exerting force (physical, verbal, emotional) on another, trying to pass it off as love. This is an illusion. If they are jealous, don't let you have a say, threatening, put you down, act differently to you in public or private, control your behavior, force you do do things you do not wish to do, are repentant one day, then back at it again the next, then it may be time to cut them off. Problems, struggles, and disagreements will occur in any relationship. It is how you and your partner deal with them that sets a relationship apart as healthy or not.
It is said that hurt people hurt people. I believe this is the cause for most bullying. If someone is bullied or abused, it creates an imbalance of power, or a feeling of powerlessness. In order to fill this void, they in turn gain power by putting people down. If everybody was respected, I think nobody would be driven to exerting power over someone else. Besides this, there are other reasons for bullying. Perhaps it is out of revenge or malice. Or maybe one feels threatened by someone else, and so wishes to control them.
Because the problem is in the heart, you cannot control it. Behavior is easy to control. It's called laws. Changing someone's heart can only be achieved by love. You cannot melt an iceberg with a sword, you need a gentle candle. Therefore, the only way to cure bullying would be to change society. Like that's gonna happen anytime soon! In the meantime, the little things one does influences the world around them.
Identify with the victim. Not all the attention should be focused at the perpetrator. This entails being a friend, just generally listening
Love your neighbor. Your neighbor being those around you. Friends, enemies, family. Treat everybody not how they deserve, but how you would want them to treat others. Don't exclude people, don't put them down
One last thing to keep in mind is that no matter how many times one repeats something, no matter how hard one tries to convince someone, no matter how wise the advice is, everyone will do as they see fit.
"Faithless is he who says farewell when the road darkens." -J.R.R. Tolkien
“I imagine one of the reasons people cling to their hate so stubbornly is because they sense, once hate is gone, they will be forced to deal with pain.” -James Baldwin,