You know, a small patrol "maneuvering to prevent you from disengaging easily" would make sense, IF there were mechanics to allow nearby fleets to join a battle that's already in progress in the same way the player can. And, of course, provided the battle is in proximity to another fleet which, when combined with the first, makes them (ostensibly) strong enough to take on yours. Factions could be made more distinct by their willingness to commit to slowing you down and holding for reinforcements, the closer to faction-aligned markets and systems, and the more fanatical they are, the more likely. Eg. Pathers would do everything they can to make sure you get overwhelmed; a Hegemony captain puts the needs of their faction first and can sustain some losses in the name of bringing an enemy of the state to justice, but recognises when they'd be no match unless adequate reinforcements really close by; Independent privateers might not be able to count on the support of other fleets and any losses would be costly.
Such a mechanic is a whole other can of worms though. It'd probably mean having to have the overmap simulation continue during battles albeit at a much, much slower rate. Or just using some kinda maths to emulate their travel time. It'd avoid the frustration of an enemy fleet just on the edge of being able to join a battle against another and somehow being there instantly though.