The ego is a very important part of our human operating equipment. Its job is to help us survive. We need it to stand up and get through the day, get things done, and more. It also tries to protect us by keeping a lid on our feelings so they don't get us into too much trouble. There is a balance between having a healthy ego, and having an overworked ego that's too busy managing unresolved feelings.
So, the ego will suppress our feelings to some extent, because that's its job. But it's part of OUR job to deal with our feelings -- examine and release as needed. That's part of emotional health and well being. Counseling, therapy, exercise, sharing, expressing, crying, loving... all help us to stay emotionally healthy.
You asked about suppressing happiness. If the ego thinks you'll get in trouble by appearing too happy, it will suppress your happy expression to try to help you survive. You pick up patterns like that in childhood, but then they go unconscious as you grow up, and it works on autopilot. Then you wonder why you're not happy! But you can learn to release the old patterns. Not easy on your own. Best done with a counselor or therapist who can help guide you.
Hope that helps.