The first relationships we have would logically be the least likely to succeed - because they are the ones in which you are the least mature due to inexperience. No matter how long you wait for that perfect piece of the puzzle to come along - it isn't just about them, it's about you as well! Turning down what you would consider "risks" (is it not always a risk - one of the greatest there is?) does not help you grow and it does not prepare you for the future.
Now, some people here think that extroverts and people that generally put their hopes and feelings on the line for someone else more frequently, are actually more shallow and careless than introverts. I'd say absolutely not, those people are learning more than we could ever understand while clinging to some kind of false purity, trying to keep our hearts intact for the "right moment". Actually you are not preserving anything - there is nothing to preserve if you are a clean slate. You are just postponing your development and justifying that in different ways.
It's concerning for me when I hear people tell others to just wait - that it's "okay" to be selective. Especially when what we are calling "selectivity" is actually just the perfect excuse for an INTP to live within the boundaries of his insecurities without having to step outside his comfort zone. Let's get our terms straight, we aren't victims of selectivity, we're victims of fear, insecurity, hesitation, self-sabotage and social anxiety. Not all INTPs are like that, that's simply what could happen, and what is at the root of the hopelessness transmitted in many threads on this board.