A lot of the focus on internal work is typically oriented toward the person working inward on whatever tensions, blockages, etc. come up. However I think it's also worthwhile to look at internal blockages as they show up in the relationships you have with people in your life. Internal blockages are bound to come up by the very fact that any relationship brings with it conflict. Such conflict can either become rooted within you, festering as resentment and anger, or it can be worked through with each side feeling acknowledged and honored. I prefer the latter approach, but I know the former approach all too well, as does most any other person. It is all too easy to let emotions fester within, especially when it relates to other people and if you are in a situation where it feels impossible to find resolution with the person, it often feels like there can be no closure at all. However, I think closure can come about, regardless of whether you have it with the person or without.
The way you recognize an internal blockage with a given person is quite simple. Think about the person. What is the emotional response that comes up when you think of the person? Do you feel you can express that emotion to the person? If you find that what you feel is negative and yet you also feel you can't easily communicate to that person what you are dealing with is an internal blockage which effects the relationship. That internal blockage will always be there until you work through it. It will show up more when you are interacting with the person, but it'll also show up when you think about the person or remember an experience. Such an internal blockage can cause you a lot of pain and create divisiveness in the relationship if you are still in touch with the person. If you aren't in touch with the person, it still gives that person power over you because of how they make you feel.
There are a couple ways you can work with such blockages. If you are in contact with the person, what you can do is use meditation techniques that help you to be present with the emotions and dissolve the tension around those emotions. For example, I like to use the Taoist water breathing meditation, which dissolves blockages and tensions. As it dissolves those blockages and tensions, it release the emotions, which gives you a chance to work with the emotions. you might find that you enter into a dialogue or replay a memory, but do so in a manner where it provides a solution. Another technique, which can be useful is a variant of the Tibetan Chod technique, where you create a thought form that represents the blockage and ask it what it wants and needs. Then you feed it what it needs, in order to transform it into an ally. That ally can provide you useful information for resolving the conflict with the person.
In the case of the above techniques, you are still in touch with the person and have some type of relationship with them. To get optimal benefits from those techniques you should plan on having a conversation at some point with the person in order to discuss what came up as you did the dissolving work. It may not be an easy conversation, but it will be ideally a liberating one for both of you. But what do you in a situation where you can't contact the person you have issues with?
My suggestion is to do a banishing ritual. I've posted before about several types of such rituals you can do, where you banish the person from your life. The value of such rituals is that you create closure of yourself by destroying any remaining link between yourself and that person. After doing such rituals, I've found that I feel much better emotionally, because I no longer feel tied to that person in the way I did before. in fact, I don't feel an emotional response to the person. I know because I've actually run into a couple such people, after I did the banishing ritual, and instead of feeling the anger and hatred I'd feel before, I felt nothing. Indeed, if anything I felt empowered because I as no longer letting them have any control over me.
Regardless of what approach you take, its important to recognize and deal with the internal blockages that come up in context to the relationships you have. By recognizing and working through them you free yourself of unhealthy attachments that keep you and those relationships in a place of dysfunction. It is better to find closure than to continue to hold onto such blockages and the tensions they create.