A second chance should come with a clearer agreement than the first one had.

Second chances often rebuild the conditions that produced the first failure. Both people want to move on, so the agreement stays as vague as before, held together by good intentions and a hope that things will be different. Vagueness is usually what broke, because neither of you knew precisely what had been promised. Specificity is not distrust but the thing that makes a fresh start survivable.

If you are giving or asking for another chance, write down exactly what will be different and how you will both know. Agree what happens if it slips again, while everybody is still calm.