I've said it before, and I'll say it again: Every person in your life should help you grow and should motivate you to succeed. But this is two-fold. You should be doing this for people in your life, too. Especially your significant other.
There are several key elements that are necessary to sustain a long and healthy relationship. But rather than boring you with the same redundant tips, I'll use an analogy.
In a lot of ways, relationships are like flowers. And when you choose to be in a relationship, you become a gardener. Flowers need sunlight, water, carbon dioxide, and nutrients/soil to grow and flourish. Take away any one of those, and a flower is going to struggle to survive.
In this analogy, water represents attention. If you aren't hanging out with your significant other, learning about them, and putting in the effort, the relationship will wilt and die. People bond over shared experiences. If you're not willing to devote your time to someone, and the relationship fails, then you really only have yourself to blame.
Sunlight represents compassion. For a relationship to flourish, you need an emotional connection. You need to listen to your partner's problems and help them get through the tough times. You should constantly give your significant other love and support. Life gets tough, and sometimes we need a boyfriend/girlfriend to show us that light at the end of the tunnel.
Carbon dioxide represents language and actions. Plants take in carbon dioxide, but humans breathe in oxygen. Just like breathing in the wrong kind of gas can be harmful, your behavior can be harmful to people. If you mistreat your significant other, whether it be through cursing or manipulation or physical abuse, your relationship will crumble. Love can be given, but it can also be retracted. So don't take it for granted.
Nutrients and soil represent life circumstances. You need to make sure that you're ready to take someone into your life. If you have a lot of personal problems to sort out, jumping into a relationship isn't the best idea. Don't let someone grow roots in an environment that isn't safe or healthy for them. That's just selfish.
It's also important to note that too much of a good thing can actually be bad. If you over water a plant, you can kill it. In that same way, if you're too clingy and you smother your significant other, that may be a turn off for them. If you're always available and reliable, they may take advantage of your kindness. People can become numb to compliments and loving language if they're overused.
Obviously, then, balance is important. It's good to know the right qualities to possess, but relationships should never be forced. Communicate with your significant other so you can understand their boundaries, and, as a result, be on the same page.