Keeping romantic options may be human nature.
Master P once sang, "I can be your n*, he can be your man. Ain't no need to leave him, everybody need a backup plan." That was back in '97, was Percy Miller onto something? Our buddies at Shine think he may have been. Quoting a story from Psychology Today, they said that people have an emotional tendency to keep 1 on the backburner. Or said differently, there's a susceptibility to sticking with good enough in the hopes that 'the one' comes along.
While the concepts are slightly different, the implicit message is that options are kept open. This is probably a good thing to do in the early stages of a relationship or in a f*ck buddy scenario, but this is tantamount to self-sabotoge in a long-time monogamous deal. It's also a recipe for complacency in 2 senses. First, why would you work hard on your current relationship if you're jumping ship at the first sign of New Found Man (or the West Mindies, depending on how you roll)? And you're probably not out there pounding the pavement (or dating sites) to find this new paramour because actively seeking a new gig while stringing someone else along sometimes makes us feel bad about ourselves. So, it's the worst of both worlds. Not actively engaged in 'making it work' and not having the balls to just leave. Maybe it's part of the same phenomenon that wires the brain to always keep a space for first loves.
On the other hand, is it possible that some relationships are saved by having a backup plan? We can imagine a situation in which people can 'take it 1 day at a time' because they've either got someone on the hook back home or a hope that McDreamy is waiting in the wings. Is it a little weird and emotionally dishonest? Sure, but sometimes little mentiras (even to ourselves) get us through the day. Sometimes the Hernan Cortes approach of burning your ships is a little imprudent. Thoughts? Anecdotes?