The Progression
Freddie became a regular at the Puckett house, even on nights when her mom was not having a party. It was fun hanging out at her house. There were no rules ever. Sam's mom seldom showed up at work, so on a typical day he would wake up and in the house it would just be him, Sam, and Pam. He and Sam would get up and he would fix them breakfast. Most days they would go to her neighbors house and walk their dogs for them because they were elderly. In return they would let them use the pool. Just the two of them, not her mom and her mom's friends. When they got back from walking the dogs Pam would have changed into another bikini for the day and call her boyfriend of the week to buy them lunch. After lunch is when they would go swimming, well a half hour, there were some habits Freddie could not break. In the evening he would check up with his mom, then go back to hanging out with Sam all day.
He started spending most of his time with Sam and her mom. To his shock, his mother was not upset about this, well of course he was also not being completely honest about where he was staying. She had recently started a serious relationship with a neurotic doctor so she was accepting his new little bit of independence a lot better.
What developed over the course of the summer was something that no one in their right mind would have guessed though: he started falling for Sam. At first he thought it was just a summer crush and did not want to think too much about it, but he gave in to his feelings about a week and a half after the time he spent the night there. At first he felt bad that he was not completely honest with his mother about his relationship with Sam, but knew she would be judgmental and he did not want to deal with that right now. After a while Freddie started feeling less guilty because Marissa's relationship with Dr. Bluth was progressing a lot faster than Freddie had expected and thought if she can do it, so can I.
Both Sam and Freddie decided that this was something really big to tell Carly and so it should be done face to face and probably by Sam. They kept their relationship from Carly until she arrived at the end of the summer so they could tell her in person.