How to Break a Met Fan’s Heart, version 673: “I don’t want to leave. I want to stay here all my career.”

That was Starlin Castro talking Friday night before he and the Cubs faced the Mets in the opener of a four-game series at Citi Field. A certain segment of Met fan has fixated on the Cubs’ shortstop as a possible solution to one of the team’s glaring trouble spots, but he sounds happy in Chicago. Or maybe he’s just really good at saying all the right things.

Either way, he is not publicly clamoring for the door, even as the Cubs have loaded their baseball pantry with elite shortstop prospects. One of them, Javier Baez, is playing next to him at second base right now.

Maybe Castro really wants to be around for the hoped-for day that Chicago’s young talent blooms together. That wait-for-it concept must sound familiar, Met fans.

Still, Castro knows it’s not ultimately his decision, something he said several times Friday in a five-minute chat with a small group of reporters. “Whatever happens, happens,” Castro said. “I can’t control this.

“I know myself. I know I can be a good player and I know a lot of teams can want me. But I’m here and I don’t want to leave here. I feel comfortable here and I want to be a part of this team when we compete, when we win playoffs and stuff like that.”

Whatever happens — or doesn’t — it was difficult Friday not to indulge in a little fantasy baseball with Castro batting cleanup for the Cubs against Zack Wheeler. Both the Mets and the Cubs have pinned their futures on these kinds of young players, but they don’t just develop them to fill positions on the field — they’re commodities, too, to be used to fill roster holes.