Gar’s mother Maire died in the days following his birth, so S.B. is his only close family.
As Gar is his only son, S.B. O’Donnell totally depends on him. But he is unable - at any stage of the play - to express his love for his son or sadness at Gar’s leaving. S.B. says “I’ll manage rightly” to Madge, but we get the impression that he is trying to convince himself.
Madge tells Gar, “He said nothing either when your mother died.” This indicates that S.B. is unable to express emotion at anything - even the devastating death of his young wife.
In some of his last lines in the play S.B. says “I was too old for her, Madge, eh?”, showing that he still thinks about Maire more than he lets on.
Perhaps Madge is the best judge of his character when she says “just because he doesn’t say much doesn’t mean that he hasn’t feelings like the rest of us”.
Madge is the only mother figure Gar has ever known. Their easy intimate relationship is evidenced in the opening scenes of the play. Gar Private also admits, early in the play, “Madge, I think I love you more than any of them.”
Gar Public does not say this aloud, so like many of the emotional feelings in the play this sentiment remains unspoken. Madge herself is clearly upset by Gar’s departure. This is shown in her final monologue.
It is also apparent in the stage directions near the end, when Madge takes the money she has saved to get her “feet done” and slips the envelope into Gar’s coat pocket.