The code snippet below demonstrates two techniques that you might use here. One, if you have data in a string ($user_input) you can open a file handle to that string by providing a reference to the string instead of a filename. Two, if you set $/ to the empty string, you can read from a file handle in paragraph mode, i.e. <$file_handle> reads chunks separated by blank lines.
use strict;
use warnings;
use Data::Dumper;
my $user_input = <<EOI;
first para
some text
second para
more text
EOI
local $/ = '';
open my $string_handle, '<', \$user_input;
my @para = <$string_handle>;
close $string_handle;
chomp @para;
print Dumper \@para;
If you then read the file handle in list mode (my @para = <$string_handle>;) you get all you want in one go. What you need to be careful about is that your manipulation of $/ does not affect other code, so usually one would use local to avoid that problem.
