When you have someone else in your life, you will have to deal with and start trying to accept the fact that your life cannot remain the same. Most relationships fail because people cling to their old ways and refuse to adopt necessary approaches and adapt to unfamiliar and uncomfortable situations. The whole point of being in a relationship is so that your life can change. And for it to change, you have to be willing to. You do not like changes because you love the way things are now. But changes will not be changes forever. If you learn to adjust to them then they will become part of your new self and your new life. To change properly, meaning that the right changes are made and that they can be beneficial, one has to know first what one needs to change. One basic fact that can help and you must already know is that everyone is different, including you and your partner. You may have agreed to build a relationship together, but that does not mean that you somehow changed your identities. And when there are differences, there are discords. To avert disagreements, find out things about you that are likely to cause them and do something about it.
Nevertheless, changing yourself is not all of it. Seeing how you and your partner have altered and are changing each other's life must be done as well. Notice both positive and negative differences that have occurred as a result of your relationship. This is how you determine if the relationship has produced the aimed outcome and what course of action that must be taken if you plan on staying together. Let us take it one by one, starting with in what ways your life has been transformed by your partner. You may feel like you are a lot better person now because they are a good influence on you. They remind you that everyone has feelings so you treat them more nicely. They explain why there are rules in public places so you begin to follow them. They find and tell you the good things that you have so you no longer loathe yourself. They also complete you by bringing the things that you need. Their confidence relieves your doubt, their courage calms your fear, and their wisdom ends your folly.
Being a good partner is not particularly similar for everybody. Different couples will require distinct changes and produce dissimilar effects. While all relationships welcome endearing qualities such as caring, fun, kind, honest, or understanding, you have to remember that those all are who you are. Whoever your partner is, you would still be that way. But since you are with this particular one, then your relationship will have its own characteristics. The way they affect your life must be different from that of other people. If you have been with more than one person, then you must be able to realize this. That is merely one end of the process, though. The other one is about what you could do for them. There must be something, or some things, that your partner needs from and looks for in you above all. Maybe it is safety, patience, candor, or sincerity. It could be anything. What you should do is look at the other relationships that they already have. They have family, friends, and coworkers. See what they do not get from those other people because that is where you can come in. Be their partner, not just have them as yours.