Morgana holds on for dear life. The water is up to her chin now, and every step she takes is half treading water. She's afraid if she lets go, they will be separated.

Although -- "Doctor, you are injured, if I could make my way to the other side of the door, I could pull you through." She doesn't think his injured shoulder could handle it.

Since they do not know where the water source is, other than outside the door, it's the only thing she can think of.

That does, of course, mean separating, contradicting her previous statement.