The first week after the guys go to the Arctic, Penny goes out almost every day with her friends. She takes advantage of their absence to catch up with her old circle of friends. Since she has become one of the guys, she has neglected her old group. Penny has a lot of fun the first week. She doesn't even think about them.
It doesn't mean anything that she avoids looking at their door when she passes by it.
The second week, Penny gets really upset when she sees a couple sitting at their table on the day they usually have dinner at the Cheesecake Factory.
When Sheldon first told her about his expedition to Arctic she had been a little bothered, but had shrugged it off. The first thing she thought was how much she would miss Leonard.
After two weeks, the only thing she wishes would happen is Sheldon knocking on her door while calling her name.
Every Halo night she breaks into their apartment and plays the game alone.
She never thought she would miss Sheldon's complaints.
After one month, she tries not think about how lonely the next two months will be.
The last two weeks of the second month, she takes some days off and goes to her parents' farm in Nebraska.
She spends almost her days eating orange Popsicles and taking care of her mother's roses.
When she goes downtown, she buys a book about physics. She reads the book imagining Sheldon's voice explaining the concepts to her.
It is the only time in two months that she doesn't feel alone.
Penny starts to watch Doctor Who after she comes back from her trip.
She falls in love with the relationship between Doctor and Rose.
She thinks about Sheldon's reaction if he were there with her and she smiles, satisfied.
The day they arrive, Penny isn't expecting them.
She hears a noise outside and goes to see what it is. When she sees Sheldon standing in the doorway, she screams his name and runs toward him, into his arms.
Her heart skips a beat when she feels his arms around her waist and his head pressed against her hair.
She knows now that everything will be okay and she won't feel alone anymore.
He's finally come home.