Is it morally wrong for a person (X) involved in a romantic relationship with a person (Y) to leave Y to pursue her romantic interests towards Z who happen to be a teacher of both X and Y? In general, is it okay for teachers and students to date each other?

There are two, independent questions here: (1) is it morally permissible for X to leave Y to pursue another relationship and (2) is it permissible to pursue a romantic relationship with a teacher. At least, I don't see how answering (2) is relevant to (1). If X's relationship with Y (1) is unsatisfying or otherwise deficient, it's permissible to leave. Perhaps my colleagues will see something here I'm missing. About (2) much has been said and thought. I suppose I think it depends upon the kind of teacher. I think it's permissible to have a relationship with a ski instructor, maybe a yoga instructor, a Sunday school teacher, or other kinds of teacher where the stakes of engaging in the relationship aren't likely to have an adverse effect upon the class or others in it. University classes, however, where grades are distributed are otherwise, since the process of grading is likely to be corrupted by romantic relationships. By corrupted I mean that grades and letters of recommendation are likely to be distributed in unfair ways when issues of eros, intimate affection, and romance intrude. For that reason, not only romantic relationships but relationships that are otherwise too intimate should be refused in the context of university classrooms (consider a parent teaching a child). A professional distance is proper. For related reasons, I think, a professional distance is proper between therapists and their clients (i.e. the therapeutic process can be corrupted). Now, I realize that there are challenging circumstances some teachers and students face when it comes to romance--for example, colleges and universities that are situated in remote areas where people face a significant shortage of potential romantic and sexual partners. Or a successful and mature romantic history prior to engaging a teacher-student relationship (e.g. where an already married spouse wishes to take a partner's class) may suggest exceptions. Things might be especially difficult where these circumstances are combined, e.g. where those involved a prior, settled, mature romantic relationship in a remote location wish to engage in a teacher-student relationship. Nevertheless, my position is generally to prohibit romantic and sexual relationships between university teachers and students where grades are distributed. Special cases can be judged by the relevant dean, but as a general rule, I think that prohibition important to preserving the integrity of the class. After the class is over, after students graduate, and with regard to students who do not and will not appear in a teacher's classes, things may, however, be different. Patience can be an important virtue here.