Arnold Schwarzenegger -- Back On the Hunt

Arnold Schwarzenegger has accepted that his marriage is over ... and we know this because he was all over a 25-year-old chick at a party over the weekend.

Arnold was at Bagatelle restaurant in West Hollywood Friday night and lasered in on a 25-ish-year-old brunette. The 64-year-old actor quickly made his move ... with his tongue.

But all good things -- like marriages -- must come to an end, and Arnold and the chick left separately. On his way out, photogs asked him about Sage Stallone and eventually fired off a question about the chick ... but he wasn't in the mood to kiss and tell.

As for his divorce, we're told it's definitely going to happen. But here's the twist ... After the story broke that Arnold fathered the maid's kid and Maria Shriver filed for divorce, he begged Maria to take him back, but she threw up roadblocks, demanding that he clean up his act. On top of that, Maria changed her mind constantly -- one day wanting a divorce and the next wanting to reconcile.

Now we're told Arnold wants the divorce and Maria is the one who's tormented ... because she wants him back, but it's not going to happen.

Sources tell us both Arnold and Maria are now resigned to divorce, which should be official soon.