A 28-year-old patient has been suffering from gum discomfort, gingival hemorrhages and pain, especially during eating, for a week. Objectively: the gums are swollen and markedly hyperemic, especially in the area of the 43, 42, 41, 31, 32, 33 teeth, soft plaque and tartar are present, gingival sulcus is up to 2 mm deep. What is the most likely diagnosis?