The union is to draw up a strict code of conduct for love in the classroom and will not support anyone who strays.
The decision follows a litany of reports on teachers and lecturers who have ruined their careers with foolhardy affairs after failing to take or heed advice.
In one case, a prison lecturer moved in with a former inmate while still being privy to sensitive and potentially compromising information on the education and background of other prisoners.
Union executive member Mary Davis said: "The number of cases I have had to deal with is increasing." Even though individuals may think their affair harmless, it compromises wider relations as other students are likely to fear favouritism educationally as well as sexually.
Jenny Craven Griffiths, also a member of the executive, said: "The best advice to lecturers who feel attracted and drawn into a relationship with a student is 'wait'," she said.
Her prescription for quelling the passions was "duck for cover and hands off till they are no longer students. We cannot defend those who leap before they think."
Many delegates to the annual conference took issue with the tough stand.
Caroline Grey, from West Midlands branch, said it would stop the union defending members in honest relationships. "It is not our job as trade unionists to find ways for management to pick on our members."
And June Kathchild, also from the West Midlands, said it would stop people being open and honest about their sexuality. A code of conduct was important but that did not mean that those who had relationships should be disciplined.
Part of the solution was also to remove the source of conflict. "Make sure the student is moved; that their work is marked by others and that the lecturer does not teach them," she said. But the list of cases where lecturers had seriously compromised themselves and their students was too great, the union agreed.
The executive, having monitored events for a year, concluded "there is much evidence that staff who engage in such relationships may later find themselves the subject of complaints by students." Such affairs were "ill-advised, unprofessional and to be discouraged".
Mary McGarry from Yorkshire and Humberside said: "Our members are getting into the most terrible difficulties." A woman lost her job last year after leaving her husband and family for a young student who then upped and went. A lecturer whose relationship had broken up "went through the class like a dose of salts", Ms McGarry said. People needed to be steered in the right direction.