From a biblical context, we’d have to go back and read Genesis 2: 18 - we know that God created his creation accordingly and since Eve (female) was made to be the helper for Adam (male), this joining was evidently going to be passed down through generations, right down to us who are living in the present times.
Yep. Its because when God took the rib out of Adams body, his body was no longer 'whole' or 'complete' in the physical sense. Something was now missing from it. I believe that the effect of this also caused him to no longer feel 'whole' or 'complete' in a subconsious sense as well, just as God had intended imo.
So then God formed Eve out of Adams rib. And Eve experienced something similar to Adam. She also felt a sensation of incompleteness. Because she, who was once the rib, was now suddenly separated from the body which she had originated from. A body which she once made complete and which completed her also. Because it was her 'housing', her safe haven. Just as a physical body securely nests a rib inside of it and provides purpose/safety/completion to the rib in a way.
I believe this is why both men and women are subconsiously attracted to each other. Because there is an urge or a yerning to fill this now empty void inside of us so that we may feel whole or complete again. Why our bodies desire to come together instinctively in order to become one flesh again.
I think that God was very wise when He did it this way. Because I imagine that if He had formed Eve out of something that wasn't apart of Adam, therefore eliminating the subconsious urge/desire to become 'whole' again, then it would not have worked out very well due to the barbarous and sinful nature man is capable of. If that urge wasn't there, practically forcing man to desire a woman at both a physical and subconsious level, then the world would probably have been governed by a law of 'the strong rule the weak'. Woman would probably no longer be the irresistible desire of man as it is now. Because she would not have been apart of him in the first place. So the urge to come together and complete each other would not exist. Which makes it quite possible then that men would merely have treated women as undesirable slaves fit only for labor and to serve, as the physically strong would do to the physically weaker. Which would also be a problem in regards to pro creation as well. And knowing mans sinful nature in time they would probably have had no problems with settling for same sex partners if need be.
So again i say, God is most wise =)