Q: Why has the editor sent me only one reviewer's comments?
I wish I could see the comments of all the reviewers, but the editor has only sent me the comments of one reviewer. The reviewers made negative comments on my English and pointed out some formatting issues which I believe can be improved by using a proofreader. Is it okay to ask the editor to send the comments of all the reviewers?
There is no reason why the editor would not send you the comments of all the reviewers. This makes me think that, possibly, your paper was reviewed by only one reviewer. Although journals usually send a paper to at least two reviewers, sometimes, they have to make do with one reviewer in case they have been unable to get another reviewer. In such cases, the editor himself/herself also does a fairly detailed evaluation of the manuscript to compensate for the lack of another reviewer. However, you can consider writing to the editor to confirm this.