Couples and individuals tell me that they get confused when to share and when to take a breather before reengaging.
Reactive is basing your response on what your partner is doing or saying.  For example, they say “You are being difficult today” and your reaction is to immediately respond with a defensive statement or educate them on how they are being ridiculous (i.e. “I am not being defensive you are being judgmental and sensitive”).
Active is basing your response on where you stand.  Loved one says, “you are being difficult” and instead of immediately reacting, you pause to see where you are at both cognitively and emotionally.  After checking in with yourself, you may actively say, “I don’t appreciate that comment and I don’t agree”, or “when you said that my first response was to scream and yell back at you”, or  “I have been feeling a bit off today.  It started when I woke up with a headache.” The difference is you are not actually going to scream and yell if you bring it up.  You are not defending why or what you are doing. Instead, you are talking about what you are feeling and thinking without reacting to the emotion.
It can also be confusing to know when we are motivated to speak up because we feel the “need” to defend our position and when we have a desire or “want” to share.  A “need” is usually driven by anxiety and we have two options to choose from.  For example, I could say nothing or tell them off.  This is black and white thinking; an indication that our anxiety level has risen.
When we “want” to share something, we usually have a follow up question.  For example, I want to share that this is bothering me, when or how do I want to share? We may feel uncomfortable while we are thinking about disclosing or before we tell our partner, however, we have thought of multiple options in sharing and are pausing to decide how we want to move forward, regardless of our partner’s possible reactions or behaviors.
All to often in relationships, we get in the pattern of being reactionary.  This is maddening as our actions, thoughts, and moods are dependent on what and how the other person is being (or perceived to be). When we give ourselves time to weigh our options (even is this is only a few seconds), we put ourselves in charge of what we would like to be in any situation or interaction.