Si non potes reperire Berolini in tabula, ludens essetis non WIF.
Hey, get your stinking cursor off my face! I got nukes, you know.
When one side aborts from a naval combat, can the remaining fleet intercept the aborting units before they leave the sea space?
What prevents the losing side from aborting after one round of combat if they fear they are an inferior force?
You can only abort units passing THROUGH your sea area - so no, the remaining fleet can't intercept the aborting units.
Nothing to prevent the weaker side from aborting after one round of naval combat, though whether it is really wise depends a great deal on the on-map situation.