As you could probably tell, the boy Glen has a crush on Betty and in the first series, watched Betty sit down on a toilet. If that wasn't uncomfortable enough, he also asked Betty for a lock of her hair, a request she fulfilled. Their atypical relationship continued for several more episodes; it never went beyond a puppy love - well, Glen did ask Betty to run away with him - but when Glen's mother discovered Betty's hair in her son's possession, she slapped Betty and broke off all contact. This latest episode is the first time Glen has been seen since then.
By the way, the boy who plays Glen is Matthew Weiner's real life son. Weiner is the creator of the show. AdRAB a whole other layer to the relationship, doesn't it.