It seems that the way that your partner handles conflict causes you harm. You mention that it is very painful for you when he leaves the conversation or puts down the phone. Are you experiencing abandonment, rejection, or both?
Training your emotional intelligence concerning understanding also means knowing how to delimit the trigger of the emotion (the event or the situation) and the internal causes of the emotion (your needs and your subjective assessment of the situation)
See emotion as an opportunity to understand and learn things about you and your environment.
In particular on the following points:
Outside world: it indicates to us the situations and events that represent an opportunity or a threat to the satisfaction of our needs
Inner world: It tells us which need is frustrated or satisfied. It tells us about our subjective way of evaluating the situation and about our representations, beliefs, patterns, and mental rules. Emotion provides us with information about the automatic way in which we react to situations. Indeed, it indicates to us a privileged way to react, it is the tendency to the action in reaction to the emotion (to flee, to attack…). It is not by what prompts us to go in this direction that we are forced to do it, we can take the time before acting by asking ourselves if this path will help us or pose a problem.
Example: I collapse with sadness while ruminating several days after receiving the judgment of a colleague at work. This emotion brings me several useful information:
Outside world: emotion tells me that it is this interaction, and particularly the reproach, that is the source of the frustration of my needs.
Needs: the need to be valued, to value me and to have my place in a group
Perception: I give a lot of weight to the judgments of others because if someone blames me, it means for me that I am null and incapable (personal belief/interpretation)
Tendency to action: I observe that I tend to ruminate for several days and to devalue myself following a reproach, and avoid or try to do well to "fix" the reproach to the person. These emotional regulation strategies contribute to devaluing my self-esteem and my need for external approval, it is helpful to find other strategies to serve my esteem needs.
Expressing your emotions has many virtues:
Inform the other about our inner state, your expectations vis-à-vis the relationship, and our relationship to our environment.
Emotional expression helps reinforce relational behaviors that facilitate relationships and discourage behaviors
It allows you to better regulate your emotions by considering them as a useful messenger rather than as an enemy against which to fight
Expressing your emotions allows you to better integrate your life events, to tell a coherent story.
Emotional expression can be:
Individual: express in writing what you feel about yourself.
Addressed to others: allows the other to adjust to our needs in the relationship.
Emotional suppression prevents looking back on the impacts of other people's behavior. Saying nothing when something hurts us helps send the message that this is OK.
At first, most people keep everything to themselves because we have the feeling that it is not being said or we are afraid of having an open conflict. In a second step, by dint of having accumulated problems, one ends up exploding when the drop breaks the camel's back.
My opinion is that from the moment something bothers us, it is legitimate to be able to express it, on the other hand, everything depends on the way of doing it. Beyond the question of legitimacy, it is the practical question of relational balance.
Expressing your emotions and your needs allows a regular readjustment in the relationship by informing your partner about what suits you and what does not suit you. It is therefore understandable that you only wish to express them for serious things or when your tolerance threshold is well exceeded.
Listening to your partner's emotions allows you to make a comfortable place for him in the relationship and to accept it as a whole. Often, it is difficult to fully listen to the other, as we have to make room for their suffering, which can be painful for you too. Listening means making room for the other's experiences, trying to take the measure of what the other is experiencing, and understanding their representation of things, even if it seems illogical to us or the opposite of yours.
Whatever your partner is going through when he becomes upset and walks away, it seems that he struggles to express his feelings and that you personalize his behavior and make it about you. His behavior is rude however I sense that he probably faces many challenges in dialoguing.
I do understand how it makes you feel because it never feels good to be on the receiving end of someone walking off or hanging up.
It does sound though that it is more his issues than yours. He might lack the ability and emotional intelligence to process his feelings at the moment. Many people will retreat to figure out how they feel and how they should respond.
When he walks away from you, he is essentially saying: "I don't know or don't want to deal with this conversation." You can't force a dialogue, it has to be an organic process.
I am essentially telling you that your feelings are legitimate however you can't control how your boyfriend behaves. You can only change how you react to him and what importance you give to his behavior.
Another option is to subtract yourself from the situation. You can assert yourself and set boundaries. I would set boundaries ahead of having conversations with him and let him know what I will accept and not accept.
Finally, it does not seem that you want to end this relationship because you care about your boyfriend but if he is unable to change how he responds to you during conflicts, you might want to remove yourself entirely from the relationship.
I wish you well and hope that my answer will help you.