What is in a romantic relationship but a plain and simple intertwining of two hearts? It is a UNION of two people who LOVE each other and who AGREE to COMMIT to each other. It is MUTUAL UNDERSTANDING and, therefore, takes TWO to make it live.
With the "union" comes commitment, with commitment comes responsibility, and with responsibility comes EXCLUSIVITY. For what is love without effort? Responsibility means, when you enter a relationship, new "duties" emerge, big or small, in pursuit of the goal to make each other feel loved and treasured. There is now the responsibility for BOTH to assure his Love that HE BELONGS. "Belonging" implies security, and security implies the assurance that it's just the two of you and no other person stands in your way to each other. There are adjustments, and there is sacrificing a bit of freedom that one had when he was still alone, simply because, it's the two of you now.
Things need not be too complicated. The relationship remains when the two people involved still honestly want it -- when both still want to be there, when both still want to fulfill their duties to each other, and when both still want to work out differences, just to be together. However, when even just one stops, IT CEASES TO BE A RELATIONSHIP, and to this, there are no excuses. No if's, no but's.
Yes, excuses to absolute exclusivity exist, the thing on gender being the most popular, i.e., homosexual relationships are supposed to be viewed from a different perspective -- "it doesn't last so it better be enjoyed while it's there, it can't be written on paper and no marriages are legally recognized in the country, no kids are borne to seal the union, etc." To all this, I STILL SAY NO. Everything is THE SAME. This is love. This is commitment. Be it between a man and a woman, a man and a man, or a woman and a woman, it doesn't matter. Sexual intimacy, bonding, agreement, acceptance, and the promise to spend life together are all there, regardless of gender or sexual preference. IT IS STILL A RELATIONSHIP and it better made good.
Lastly, in a relationship, one cannot be having THE BEST OF BOTH WORLDS. If you want me, be here, and I'm here. If you start wanting another person, GO THERE, be with him, leave me. One cannot be treated as an old shoe here, i.e., you try out other newer pairs out there and when your feet start to hurt, you come back to the same old shoe you had. Plain and simple NO.
Remember, this is between TWO HEARTS. Both capable of loving, of being happy, and most of all, of getting hurt.
This may sound old school, but it's FAIR.