"Make sure your brain, heart, and penis are in conjunction -- they should all be in a straight line before you have sex," she says.
Concern about STDs and unwanted pregnancies can help create sexual boundaries, believes Mc Clary.
If, for instance, you're on the fence about whether or not to take sexual activity to the next level, a healthy dose of fear may cause you to pause, particularly if you're not prepared to take the necessary precautions.
Plus, not having adequately prepared for these practical aspects of sex may signal an overall non-readiness to engage in it.
At some point during their courtship, many dating couples decide its time to break down initial boundaries -- be they emotional, physical, or both -- and engage in a sexual relationship.
"You might find that you don't even like the person," Allen tells Web MD.