I am a semi-serious Arsenal fan, over these past six years, and the club drives me crazy. I can only wonder how it feels for those who have been cheering on — and wincing at — the club since said fans were in diapers.

Arsenal, would-be contenders for the Premier League championship nobody seems to want, contrived to squander an early lead and lost, 2-1 at home tonight, to Swansea City, who a few minutes ago were looking at a relegation battle.

It was a perfect example of Arsenal’s drift across multiple competitions this season, which finds them playing every third or fourth day and of late not impressing anywhere.

It led Barney Ronay of The Guardian to marvel at “Arsenal’s ability, week in, week out, to look like the best really terrible football team in Europe.”

Let’s get up to date on Arsenal anxiety:

–On February 20, the winners of the past two FA Cup competitions (Arsenal’s only trophies since 2004) hit a boulder in the road in The World’s Oldest Soccer Tournament when Arsene Wenger’s team could do no better than a scoreless tie — at home — against Championship (second-tier) side Hull City. Their punishment for that lifeless performance is a replay jammed onto the calendar next Tuesday.

–They reached the knockout phase of the Uefa Champions League, the world’s most significant club competition, and being in the final 16 is a significant development — but not so much if it is agreed your team has zero chance of winning the thing, which is Arsenal’s situation since I’ve been a semi-fan, anyway.

In the first leg of their final-16 pairing with (gulp) Barcelona, on February 23, Arsenal lost 2-0 — again, at home — which means their best hope for getting to the quarterfinals would be a 2-0 score in their favor over 90 minutes in Barcelona on March 16 and victory in a shootout in the stadium of the world’s greatest team. Or they could win 3-0 outright and avoid the shootout. Uh, sure.

–Presented with chances to take control of a league race still led by Leicester City, for crissakes, Arsenal has failed repeatedly. Since a last-shot victory over Leicester on February 14, which for starry eyed people who don’t pay close attention to Arsenal’s “come here … go away” shtick, seemed like a turning point. Ha. They were two points out of first place, at that moment.

On February 28, they lost to Manchester United 3-2 at Old Trafford, which is what Arsenal does — lose to the other big clubs when the stakes are high. They probably saved Louis van Gaal’s job, though; there was that.

Then tonight, the inexcusable 2-1 league home loss to Swansea City (which has won three of their past four on Arsenal’s pitch) which kept them from slicing Leicester’s lead to three points.

This is all very predictable Arsenal behavior. Months of what the Brits call “false dawns” followed by defeats to any competent club and more to semi-competent teams.

Up next?

The major issue now, aside from “Arsenal being Arsenal”, is their status as putative contenders in three competitions — the league, the FA Cup, the Champions League.

Despite generating enormous revenue, Arsenal clearly does not have the depth of talent to compete in three competitions simultaneously, especially when they are having great trouble scoring goals.

It all is a sort of spinelessness that reflects a soft team made up of little guys who like to make square passes, with nobody dangerous in front of goal (now that Olivier Giroud has gone to pieces).

It is too bad the Barcelona leg of the Champions League isn’t next week (or this week, for that matter), so they could take their spanking in Camp Neu and escape the CL.

So, the upcoming schedule for a team already thin and reeling:

–Away to second-place Tottenham in the league on Saturday.

–Away to Hull City in the FA Cup on Tuesday.

–Home to West Bromwich in the league on March 14 — unless they beat Hull City in the Cup replay on Tuesday, in which case they would likely be home to Watford in the Cup final 16 on March 12 or 13.

–The Champions League beatdown at Barcelona, on March 16.

–And away to Everton in the league on March 19.

And somewhere in here they may have to make up the league game with Everton.

The most realistic fans already are thinking of “triage” — which competition to concentrate on and letting the others die. The Champions League is a lost cause. Move on.

The question then becomes … “league or Cup”.

The league is a bigger deal, and Arsenal hasn’t won it since 2004, and it is winnable this year — if some team can keep their wits about them and overcome the jitters, and that is not something Arsenal has shown any facility for, these past 11 seasons.

I feel bad for their real fans, who pay the highest ticket prices in the league, just to be put through these we-can-do-it-no-we-can’t psychological games/torture.

It is about the only facet of the game Arsenal can be counted on to deliver.