Watch much less TV and read far more books. TV/Movie storytelling is different from book storytelling. If you are thinking in terms of facial expressions, your storytelling apparatus is running in video mode, not prose mode.
Both prose and video are limited media. Prose has limited access to visual information; video has limited access to mental states. In both cases you have to tell your story using the things that your chosen media is good at and avoiding those things that it is bad at. Once you get it properly tuned in, you will do this naturally.
The problem for anyone writing prose today is that most of us actually spend more time watching TV and movies than we do reading. TV now provides most of our cultural touchstones. Chances are that conversations around the water cooler will be about the latest TV sensation, not about the book you just read. With few exceptions, we look to TV for shared interests and to books for individual interests. And that keeps us glued to TV even when we are interested in writing books.
Descriptions of facial expressions are rare in books (and only effective when exceptional). Book dialogue is not remotely like real speech. It moves far more of the context and emotion of the interaction into words than would ever be the case in real life. (Movies may do the opposite, putting less into words and more into actions, to give the actor more to do.) To be successful in writing prose dialogue, you have to figure out how to move the emotion into the words.
There are all kinds of ways to do this, many of which come down to shading and tone that really have to be learned by ear. But there is one general principle I think is sound, which is that all dialogue is conflict. Even between lovers, each person wants something from the other, and is negotiating to get that thing. They may not fully understand what they want, and the will usually not articulate it directly, but what they say is designed to subtly (or not so subtly) move the other person in that direction by appealing to sympathy, greed, the protective instinct, etc.
There is a core of wheedling, of desire, of hope, of expectation, of recrimination, of forlornness and despair in every dialogue. You have to ask yourself in every line you write, what does this person want from the other in this moment, why are they afraid to ask for it outright, and what, given who they are and what they fear, are they willing to say to try to get what they want. And, of course, every response they get is driven by all the same things. Conversation is chess, it is fencing, it is, sometimes, all-in wrestling. Find the conflict within and the conflict between and let it flow into words and you will have your dialogue.
That is only going to come naturally from tuning your storytelling apparatus to prose mode by attentive emersion in prose storytelling. Turn off the TV. Pick up a classic novel. (You need to read people who will do this better than you ever will.)