Hmmm. I don't relate to this. I've had the same best friend since the 10th grade and even if we go six months without talking, we pick up where we left off...kind of like what Alexx is talking about.
If you're talking about romantic relationships, I'm just wondering if you're very young. If you have the temptation to write people off that quickly when butterflies die down, you're not even giving them and yourself a chance to develop a real, lasting relationship. There's something else you're not experiencing by giving up that way. I think I related more to what you're saying in my late teens and very early twenties, but not really at all now, at least not within the last five to seven years of my life. In fact, I've learned by my last LTR that something has to be SERIOUSLY, SERIOUSLY wrong in the relationship for me to even be able to walk away from someone I've fallen in love with and committed myself to.