9:30 AM PT -- Unsurprisingly, Jonathan Majors arrived to court with Meagan Good by his side ... we've seen the two together a lot as of late, including Tuesday when they grabbed food together in NYC.

Jonathan Majors is finally going to trial for allegedly roughing up his ex ... and we might even hear about past allegations involving other women, if the judge allows it.

The actor's set to appear in court Wednesday in NYC, where the trial is scheduled to finally begin ... this after several delays. Remember, Majors was arrested and ultimately charged back in the Spring with misdemeanor assault and harassment.

His former girlfriend, Grace Jabbari, claimed they got into an argument in March, and he got physical with her in a car, which she says left her with injuries.

Of course, Majors has denied that from the beginning ... insisting it was him who got hurt in the spat -- which, several months later, resulted in Jabbari getting arrested by the NYPD ... although the D.A.'s office refused to prosecute her, maintaining she's the alleged victim here.

There's been a lot of info, photos and videos that have leaked out over the past several months leading up to the trial ... much of which, Majors' camp claims, depicts Jabbari, after the alleged attack, having a night out on the town and seemingly looking uninjured.

Another twist in this case is the fact a police report taken in London -- 6 months prior to whatever happened between Majors and Jabbari -- was entered into the court docket by prosecutors ... although it's remained under seal up until now.

Media outlets have filed motions in the case to have it unearthed, publicly, and a judge is expected to weigh that motion Wednesday before court proceedings kick off in Majors' trial.

It's unclear who the other party is in that London report ... but there have been rumors of other alleged possible incidents Majors might have been involved in before his March arrest.

Another element of this saga is what Majors has been up to in his personal life as this whole thing has been playing out -- namely, him starting a relationship with actress Meagan Good, which seems to have come out of nowhere ... but continues to go strong.

Good -- who hasn't addressed how she got involved with Majors, or any other details about why she's backing him -- has appeared alongside JM in a couple different high-profile court appearances ... and the two of them have been spotted in public all over the world too.

In fact, they were seen looking incredibly loving and cozy on Tuesday, cuddled up on the streets of NYC and putting on a united front.

Professionally, Major's career has been thrown into limbo -- he's lost film and TV opportunities since being accused by Jabbari, but he's been able to keep his Marvel job (for now) as Disney seems to be taking a wait-and-see approach to their leading man.

Other completed films of his have been put on pause ... so there's a lot hanging in the balance here for him. Now, we'll get to see what prosecutors believe they have against him in terms of evidence -- and more importantly, a jury's gonna be able to hear it as well.