Newline Character Missing in Memory Variable

Hello, Seders,
File /tmp/file contains:
Line 1
Line 2
Line 3
Line 4
Line 5

$ sed -n '/^Line 2$/,/^Line 4$/p' /tmp/file returns
Line 2
Line 3
Line 4

However, spaces had replaced '\n':
$ InMem=$(sed -n '/^Line 2$/,/^Line 4$/p' /tmp/file) && echo -e $InMem returns:
Line 2 Line 3 Line 4

and InMem='Line 2 Line 3 Line 4' and not
InMem='Line 2\nLine 3\nLine 4'?

Q1. Can I physically add '\n' in the sed command above?
Q2. Why the difference in behaviour?
Many thanks!
Kwon