The scene changes seem a bit too frequent here. I think it would be fine to stay on this shot, but we could add some background sound—footsteps that get louder as the person approaches.

Similarly, don't let Julian say that line; instead, use the sounds of a closet door opening and clothes rustling coming from the dressing room.

I don't think this line is necessary; adding it to Julian's character would make him seem less sharp.

That's a bit unrealistic—fountain pens aren't that fragile. I think this could be changed to "snapped a pencil on the table."

same as the above

The phrase "rumpled covers" sounds a bit odd—the blanket should be smooth, but the area between Adrian's legs would be raised high, and the bulge in the blanket would create wrinkles.

It doesn't specify what kind of rhythm this is; it actually refers to the twitching of Adrian's hand, which causes the blanket to rise and fall—first high, then low—with the rate of change accelerating.