The post that helped crystallize it properly for me: english.emmaclit.com/2017/05/20/you-
The idea of emotional labor has gotten a lot of traction lately online, but the main problem I keep seeing is that people have a hard time pinning down exactly what it is, as opposed to being able to point to various anecdotes that they think exemplifies the concept. This in turn leads to confusion, and often a significant subset of people (usually men) who find the anecdotes and the conversation around it to sound too much like "haha men, they suck so much, amirite?" So this is going to be an attempt to lay down a clear definition of emotional labor without the baggage.
Emotional labor is essentially a name for a managerial role in a relationship. This takes on a few different concrete forms.
The first is management of the household, appointments, shopping, and other assorted tasks that are generally shared across couples and/or housemates. Sweeping a floor or cooking dinner is not emotional labor, but being the person who makes sure that those things are accomplished is. It doesn't matter whether you get the floor swept by doing it yourself, asking your partner to do it, firing up a Roomba, or hiring a cleaning service; what matters is that you are taking on responsibility for making sure the task is done. This is why people who say that they would be happy to help with the housework if you would just tell them what needs doing are being a lot less helpful than they think. They're taking the physical labor component of the task but explicitly sticking the other person with the emotional labor component.
The second is taking responsibility for the likes, dislikes, feelings, wants and needs of other people who you are in a relationship with (and to be clear, it doesn't have to be a romantic relationship). Stereotypical scenarios that are covered by this kind of emotional labor include: the hysterical girlfriend who demands that her boyfriend drop everything he's doing to comfort her, the husband who comes home tense and moody after a long day at the office and wants to be asked how his day went and listened to and have validating noises made at him, noticing that the other person in a conversation is uncomfortable and steering the conversation to a more pleasant topic without having to be asked, helping a confused friend talk through their feelings about a potential or former partner, reminding your spouse that it's so-and-so's birthday and that so-and-so would appreciate being contacted, remembering birthdays and anniversaries and holidays and contacting people and saying or doing the right things on each of those dates,
Notice that that last emotional one crosses over into material relationship management again. I'm pretty sure that this is why the confusion is so rampant over what exactly emotional labor is, because other people see the cards and the cooking and whatnot and assume that those things are the emotional labor. They're really not. The emotional labor is the responsibility/management aspect. They're also the part that's invisible and easy to take for granted, particularly since management of other people's feelings is usually assumed to include not letting the other person feel bad about their lack of emotional labor skills.