"Relationship" is not a Bible word, at least not in the good King James translation. Yet it is a very good word in that it expresses an idea dealt with often in the Scriptures.
In male-female terms having a "relationship" is a nice euphemism for describing sexual activity without being blunt. In more general terms the word refers to "the state of being related or connected." In the course of a lifetime we have many contacts and many connections, therefore many types and kinds of relationships. These can be good, bad, or indifferent, depending on the circumstances. A relationship may be close or casual, real or artificial, legal or illegal, proper or improper. In any case, all IMPORTANT relationships are dealt with in the Scriptures. Certainly the Bible speaks extensively about the "relations" between a man and woman, both in and out of marriage. It also deals with the relationship between parent and child, brother and sister, master and slave, friend and neighbor, friend and enemy etc. (You may want to read some of the references, such as 1 Cor. 7:1-11, 1 Cor. 6:13-20, Eph. 5:22-6:9, Rom. 12:3-21.) As you can see, specifically and in general, God has instructed us about the ins and outs of good human relationships. And surely this is something we all need today.
Anyway, like it or not, for better or for worse, as fellow human beings we are all forced to "relate" to one another in life. We cannot avoid such relations. The only question is whether our relationships will turn out to be good or bad, pleasant or unpleasant. Please note that the question of interest here is not how effective, or workable, a relationship might be. Many relationships seem to "work" quite well even when they are not really satisfying to anyone. A relationship may be held together by force on one side and fear on the other, as in the case of a mean master and a frightened slave. A relationship may be built on sheer dependency, as when a helpless wife stays with an abusive husband for economic reasons. A relationship may be based on mutual needs, as when one person has to sell what someone else needs to buy. They do not have to like each other in order to do business. So, human relationships are not always formed out of the best conditions. Nor do they have to be in order to exist and/or survive.
A GOOD relationship between human beings is different. It is more than a relationship that manages to survive its own unpleasantness because there is no other choice. Rather, it is a happy relationship that satisfies everyone. What makes it so? The recipe for "A Good Relationship" calls for many noble ingredients; but perhaps two are most vital – respect and trust. How can husbands, wives, parents, children, brothers, sisters, friends, or neighbors, have a good relationship with each other in the absence of respect? How can they have a good feeling toward one another without trust? Bear in mind, however, that respect and trust must be mutual, on both sides.
One other thing. Human relationships involve human beings. Humans are notoriously imperfect. For this reason there will never be a PERFECT human relationship in this world. But, there can be good and satisfying relationships between those who respect and trust one another. This is the kind of relationship the Christian faith tends to produce.
As already stated above, we have all kinds of relationships in this world, most of them purely human. I called them "human" relationships because they occur naturally between and among human beings on account of their mutual humanity. We rejoice or suffer in these relationships depending on how they work out.
On the other hand some of our relationships are more than human. They transcend the human. I am not referring just now to the long-standing relationship most of us have with the devil, though this might well deserve our attention. Nor am I thinking of the relationship we have with pet animals. Some of these precious cats and dogs may SEEM to be smarter and more faithful than people; but in reality they are sub-human creatures that merit only sub-human consideration. Also, I am not thinking of the relationship we develop these days with machines of all kinds. Some of them (TV) do indeed talk to us day and night in the most human-like tones, and we love them dearly; but they are not really human. And certainly they are not spiritual. We do have relationships, however, that derive from a spiritual base. While they may exist at a human level, their origin is in a realm higher than that. These relationships have to do with God, who is spirit (Jn. 4:24).
For example, the Hebrew writer (4:13) spoke of God as "Him with whom we have to do." This means we all have a relationship with God whether we like it or not. We may say, to ourselves if not out loud, that we "don't want to have anything to do with God." But this will not work. God is our Creator. He is our Father, at least through Adam. Therefore, we are "related" to God. He is related to us. He deals with us, so we are going to have to deal with Him sooner or later. But even this is not altogether the point
The spiritual relationships I have in mind are those made possible by Jesus Christ. As I understand it, when one becomes a Christian a lot of new relationships are created. Basically they go in two directions. One is vertical, going upward, having to do with our relationship to God through Christ rather than Adam. This relationship is not based on flesh but on faith, as Paul said in Gal. 3:7-9. The other is horizontal, going outward, having to do with our relationship to others who have been "obedient to the faith" (Acts 6:7). One simply cannot be born into the family of God without acquiring all the attendant family relationships this involves. Therefore Christians have two basic relationships in Christ. One with God, the other with their fellow disciples. There is not a third.
Yet in the modern religious world we hear a lot about the importance of a "church relationship." What this usually refers to is an "affiliation" with a denominated religious organization, otherwise called a Church. In most cases being "affiliated with the Church" means about as much to people as being affiliated with a good civic organization. For a lot of folks it is not even this important. They like their Club better. But really it does not matter, because being "Church-related" in this sense of the word is not even discussed in the New Testament anyway. No such "relationship" existed back then. At least I cannot think off hand (or on hand either) of any passage that informs Christians about their relationship to a corporate Church. Can you? Yes, there are many verses that speak of our relationship to God and our relationship with one another. But to my knowledge there is no verse telling us about the additional relationship we have with some THING called the Church. Probably this is because it is hard, if not impossible, to have a spiritual relationship with an impersonal, institutional THING.
So again, in apostolic times people who became followers of Jesus only had TWO brand new relationships to consider; one with their Father and one with their brothers and sisters in Christ. These are the true spiritual relationships that exist in serving God. If there are others I have missed them.