The 20-year-old attacking midfielder has been dropped for the weekend's clash with Watford after photos emerged of him on a drunken night out with friends in the wake of Saturday's 4-0 loss to Everton.
Grealish has been ordered to train with the Villa U21s this week and has been warned about his behaviour by club officials and although Garde has criticised the controversial talent, he understands that being in the limelight with so much disposable income can become a problem for inexperienced players.
"It's not always easy to earn a lot of money when you are young," the Frenchman said. "It's strange, it shouldn't be a problem.
"But we also have to remember what we had in our brain when we were 20.
"You cannot only blame, you need to understand and help."
But despite his understanding, Garde indicated there has to be tough love for these types of actions: "Some things are negotiable and some are not.
"There are a lot that are not because I think I am in a position where I have to give direction. I feel the players are very happy with that."