Yes, your expectation is unreasonable. Your pay rate is what you have agreed to accept for the work, and has nothing to do with what anyone else makes. If you are unsatisfied with your rate of pay you are free to address it with your boss or seek other work.
If you do choose to address it with your boss, your focus should be entirely on what you do, achievements you have made, improvements to the department, etc. You can also mention the length of time you have been working without an increase. But under no circumstances do you bring up your coworker.