outcome_array=the_text.split(pattern_to_split_by)

irb(main):015:0> s = "split on the word on okay?"
=> "split on the word on okay?"
irb(main):016:0> b=[]; s.split(/(on)/).each_slice(2) { |s| b << s.join }; b
=> ["split on", " the word on", " okay?"]

irb(main):007:0> "split it here and here okay".split(/ (here) /)
=> ["split it", "here", "and", "here", "okay"]

s = "split on the word on and include on with previous"
a = s.split(/(on)/)

# iterate through and combine adjacent items together and store
# results in a second array
b = []
a.each_index{ |i|
   b << a[i] if i.even?
   b[b.length - 1] += a[i] if i.odd?
   }

print b

["split on", " the word on", " and include on", " with previous"]