When Troy and LeVar Burton returned from their long journey he finds that a lot has changed. To start he sort of feels replaced, Hickey, Chang, Duncan, Rachel and even the Dean have all become really close with the Study Group now known as the Save Greendale Committee.
They all grew extremely close over the summer with the outings they had, pool parties, barbecues, beach trips etc. While Troy has been invited to the group outings and going on adventures since he got back he can't help but feel a little excluded socially. He feels as though he's missed out on a lot of special moments that made the group closer than ever.
While he tells them about his journey like getting captured by pirates and facing shark attacks the group look at him in admiration like he's a changed man and maybe he is. He had a lot of time to think about stuff that wrinkles his brain like his future and what he wants to do with it.
His friendship with Abed has changed since he returned while they still hang out, watch Inspector Spacetime and Kickpuncher they aren't as close as they were. Abed is always with Rachel now as they are a couple and while they have invited him to their activities he doesn't want to be a third wheel. Abed is also spending a lot of time with Buzz now as well, he's pursuing his dream of becoming a film maker with Buzz's help and in return Abed is helping him in becoming a cartoonist.
Abed and Rachel becoming a couple wasn't the only surprise romance for Troy, Jeff and Annie finally got together not long after they saved Greendale from Subway and Annie was making sure that they double dated with Abed and Rachel. Yep Jeff was truly whipped. But the biggest surprise and what hurt the most was that Britta and Duncan got together.
While he was on his voyage he spent a lot of time thinking about his breakup with Britta and how it might have been hastily done. He wanted to give them another shot and put more effort in the relationship. No one told him that they were together they all just assumed him and Britta were totally fine breaking up but he wasn't. They also apparently got together not long after the Subway fiasco, he guessed romance was in the air that week.
He found out by complete accident, he had some initial suspicions of something going by the way she referred to him as Ian instead of Duncan like everyone else and how they had somewhat flirty conversations and long looks and stolen glances. However the day he truly found out was when he saw them together on the street heading to the Red Door, they were holding hands and they kissed and he never saw Britta as happy as she was in that moment.
Troy briefly thought of admitting his feelings to Britta but he didn't want to ruin their relationship he learned a lot from the Annie and Vaughn fiasco and he also knew how rare it was for Britta to be in a committed relationship she only truly opens up to a certain number of people and Troy knew he would never purposely ruin that for her.
Yes a lots changed.