Mars in Cancer builds up tiredness and anger without saying so in time. This system considers the position adverse. The description points to a difficulty in recognizing their own energy limits in time: in a project, they may keep going past their tiredness and notice they need to stop only when they have already reached exhaustion.
Something similar can happen with anger. They find it hard to say in the moment what pleases them and what bothers them; they accumulate small discomforts until a minor situation triggers an intense reaction. The saying “A glass is filled by a stream and overflows by a drop” helps us understand why the last cause doesn’t, on its own, explain the whole reaction.
To understand that behavior it’s important to know what was learned in childhood. If outbursts won attention or advantages, that way of asking may have been reinforced. If there were limits that helped them recognize and regulate what was happening, the person may have developed other responses. It isn’t right to assume a particular childhood from Mars; the point is to explore whether that pattern is part of their history.
After the initial impulse, a moment of reflection can open in which the person owns what they feel without looking for someone outside to blame. It helps not to feed the argument at the height of the outburst and to resume the conversation once things are calm. Recognizing tiredness and making room for rest also lets them attend to their own limit before reaching exhaustion.