We do live in an era that has lost the significance of connection. We have lost the scope of understanding of how interpersonal relationships are more than just disposable moments. The feelings of the new, is unbeatable, truly they are, but it is when those feeling wain that we find out who we really are as people. I am not advocating that every relationship is meant to be the end all be all. Some are meant to fizzle and some are meant to drag on longer than they should, just as some are meant to last. If we bail, before we let fizzle out, or even sustain something longer than we should, we fail to understand and grow to the point to make something truly meaningful last.
If we fall into a cycle like you speak about in your third paragraph, we just bring a cycle of pain, rejection, unresolved loss, loneliness, and self medication through this instant soothing of what is broken.