The Sweden defender was linked with a move away last summer.
But he told Fotbollskanalen: "It wasn't actually that much. Me and the club sat down after last season and were pretty clear that the club didn't want to sell and that I wanted to stay. Something very good would come up for me to want to leave in this window. It wasn't something I needed to take a stand on."
Starfelt has managed to play two out of four league games this season. Celta Vigo has recorded six points.
"We had a very good start with two victories. It was perfect. But the last two games we have had the margins against us, especially against Villarreal (3-4), it is always hard to lose in the last minute. But two wins and two losses is acceptable, even if after that start we had hoped for a little more. In terms of the game, it still looked good."