Alexander Romanov was fiddling with his skate laces Friday afternoon, pulling them tight as he talked about his own confidence.

Six weeks ago, at the same spot in the Islanders’ locker room at Northwell Health Ice Arena, Romanov had walked a fine line between self-doubt and self-criticism.

He said then, amid a run of poor play both for himself and the team, that he understood what was positive about his game, but without being relentlessly self-critical, would never improve.

It walked a thin line between realistic evaluation and self-flagellation.

Shortly thereafter, Islanders coach Lane Lambert took the drastic step of splitting his top two defensive pairs, putting Romanov with Ryan Pulock and Scott Mayfield with Adam Pelech.

Around the same time, everyone started to see the 23-year-old Russian begin to settle into his game.

“Just, I feel like coaches started to trust me more,” Romanov told The Post. “I feel confidence in my game.”

So the timing of Romanov suffering an upper-body injury Saturday is not just unfortunate for where it is within the Islanders’ season, with the team in a white-knuckle playoff race, but for where it is within Romanov’s own developmental arc.

Lambert said after the 2-1 loss to the Hurricanes that Romanov was day-to-day, a designation made almost meaningless by how liberally the Islanders have deployed it this season.

With three days between Sunday and the team’s next game against Tampa on Thursday, there would at least be time to deal with the injury if it is, in fact, minor.

Romanov, who averages 19:27 time on ice and plays pivotal penalty-kill minutes, is as big a part of the Islanders’ defense corps as anyone.

When he went down in a heap late in the second period of a 5-0 loss to Tampa on Saturday, the Islanders held their breath — and they’ll keep on holding it until he gets back.

With the Islanders needing desperately to win at least three of their last four games to make the playoffs, there is some urgency to getting their top-four intact as soon as possible.

“He’s very reliable,” Lambert said. “And you can see the understanding that he has now garnered in trust [from] us for him.”

Romanov’s ability to throw hard, legal, open-ice hits has changed the course of games for the Islanders. With the playoffs looming, that’s more important than ever.

“You can’t let guys just walk in around you and feel the freedom on the ice,” Romanov said. “Just part of the game. It always was part of the game. It’s a tough game.”

By his own admission, Romanov struggled at times when it came to playing within the Islanders’ structure for much of the season.

That’s part of adapting to a new team, a new city, especially as a young player.

Now, though, he can play the unthinking hockey players strive for — operating on instinct and muscle memory.

“He’s evolved,” Lambert said. “There’s certain areas and aspects of how we play and the position and how we want him to play the position. It’s taken him a little while at times to totally comprehend that. I think he’s done a real good job now. I think Ryan Pulock has helped him a lot with communication as well.”

Pulock is the third partner the Islanders have used with Romanov, after Mayfield and Noah Dobson, and it’s the one that’s clicked.

On Friday, Romanov spoke of his frustration in the past tense.

“Now, all good,” he said. “Trust me.”

Soon, the Islanders hope, his injury will fall in the same category.