So if the Mane 5 left the Crystal Brighthouse on their own adventures, they always leave the doors open for misty to enter in while under Opaline's order. But since Misty is now Allies with the Mane 5, she may enter as pleased. But when she and EJ are there and the Mane 5 are out for a while, They would have some Sexy Fun time making love and not worrying about the Mane 5 coming back for the next few hours, But don't worry EJ and Misty would make sure they clean up the mess (Until they may have forgotten a few missing spots).

But in actuality, Sunny needs some security for the Brighthouse for Trespassing ponies/ Un-wanting attention, Sparky had the right idea for Booby traps back in Chapter 2.

Also EJ and Misty could make out in EJ's Place, but the Brighthouse has more Space and There's a lot to it that Misty would Consenter it her "True" home Unlike Opaline's Castle. Oh and Opaline's Castle is a 85% bad Idea for make out time since Opaline doesn't like un-welcomed visitors like the Last time, Plus She barley leaves the Castle.