I've been trying to find things on time frames. By that, I mean, is there a certain time for attraction/comfort to erode and slowly drop out?

Example 1: You number close a girl you've never met before and spark some attraction. In general, how long can you space/delay between interactions?

Example 2: You number close someone in your social circle/work/college. You've known them for alittle while and comfort there (perhaps you've even been on a date or two). Is there a 'shelf-life' to the attraction you've built if you don't see them for awhile? Weeks? Months?

I know there can't be any definite answers since it depends on the girl and the situation.

But are there any articles/books on this subject? General principles or even past experiences from you guys?

Basically, how long does it take for attraction to fizzle away between meets?