Poul Anderson 
Sentiment, Inc. [PDF ebook] 

In the future, technological advancements have rendered the heartbreak of unrequited love a thing of the past. One enterprising researcher has discovered a way to zap human brains into a state in which they become receptive to a particular person’s romantic overtures. But one fellow whose love interest has been forced to undergo the procedure against her will is more than a little peeved about the whole thing — and decides to take action.