It depends on what the reasons are. If they sound like one of a kind unavoidable complications, then let it go. It's not uncommon that SPs are juggling school, day jobs, shared in calls, travel between cities, boyfriends and families all while trying to keep their SP work secret, so things do come up. Having said that, keep in mind that some ladies double book and cancel at the last minute if both guys show up. Also, I'm pretty sure some ladies will cancel at the last minute if a regular "preferred" client wants to book. If you are low on her priority list, it's probably best to put her low on yours.
