In Catholicism there is no sin of “emotional affairs.” This has no basis in Catholicism. Rather, there are three questions.
(1) Is this near occasion of sin,
(2) Is this intrinsically evil, are your intentions good, and is this prudent
(3) are there sins of scandal or any other sins (like sins of omission),
Ans (1). It depends, in my assessment, on whether one is physically attracted to the woman? If yes, then forming any deep emotional connection with a woman can very easily become near occasion of sin to exterior acts. Therefore, flee at all costs! If a man is not physically attracted from the onset whatsoever, then given physical attraction typically does NOT develop that never existed in the beginning, there could very well be no near occasion of sin. For this reason, given many men are naturally repulsed by the idea of homosexual acts, heterosexual men can totally have “emotional affairs” with other men with no chance of it becoming romantic. As far as women, men are not physically attracted to every woman. There may be women for which one has no physical attraction whatsoever. If physical attraction does not exist from the onset, then for most men, it will likely never develop in the future. This is why a heterosexual man forming an extremely close emotional connection with another man poses almost no danger of him also forming a homosexual physical attraction. Thus, forming deep emotional connections is not always sinful. Therefore, first answer whether this is near occasion of sin!
Ans (2): No, this is not intrinsically evil even if you are physically attracted to the woman (although if you are attracted to the woman in any way it is almost certainly imprudent and very easily near occasion of sin). Your intentions must also be pure. Finally, consider the third source of morality, the question of prudence, the circumstances of the act. Are there negative effects that outweigh the positives? For example, the very fact that women think “emotional affairs” is a sin in itself (it isn’t, the sins are attacks against the sixth commandment and near occasion thereof), shows that feelings like jealousy, etc, must be considered. Therefore, to evaluate the circumstances, perform a prudential evaluation of the positive and negative effects.
Ans (3): It could very well be the wicked sin of scandal to be alone with a woman. Flee at all costs, at all costs, from sins of scandal. Therefore, a single man must make sure (unless there is proportionate cause justifying it) that his relationship with women stays to letters, text messages, and conversations in public. Never be alone with women for any extended period of time without a proportionately just reason! And if you are physically attracted to the women, then a proportionate reason of even larger weight is necessary. A substantial minority of men, particularly ones that have ever had “addictions,” should avoid ALL physical contact in dating. Period!