Why did Gaius Marius lose support from both the plebs and the Roman aristocracy after 100 BCE?

After 100 BCE, Gaius Marius lost the support of both the Roman aristocracy and the plebs due to his political isolation and the fallout from his alliance with the radicals Lucius Appuleius Saturninus and Gaius Glaucia.12

• Loss of Aristocratic Support: Despite his military achievements, the oligarchy never accepted the "upstart" Marius as an equal. His earlier unscrupulous political tactics and his association with the lawless, revolutionary actions of Saturninus and Glaucia alienated the nobility. Even after Marius turned against his allies to "save the state" at the Senate's request, the aristocrats refused to embrace him, eventually recalling his bitter enemy, Quintus Metellus, which severely damaged his prestige.12

• Loss of Plebeian Support: Marius relied on Saturninus to secure land for his veterans, but the violent, illegal methods used by his allies eventually forced him to act against them. By imprisoning and failing to prevent the lynching of Saturninus and Glaucia, Marius was viewed as a man who betrayed his friends, causing him to lose the favor of the plebs who had previously supported his populist measures.12