The honeymoon is over for Katy Perry and Russell Brand... and possibly the marriage too. Multiple media outlets are reporting that there is serious trouble in paradise for the odd couple. One source reveals that prior to the holiday there were major fireworks between the "Last Friday Night" singer and the Arthur actor. The insider tells Us Weekly, "They had a massive fight. She was like, 'F--k you. I'm going to do my own thing.' Russell replied, 'Fine, f--k you too.'" She ended up basking in the beach surf in Hawaii, while he spent the holiday in a pub in Cornwall, England. Over the past couple of months, rumors have been swirling that the couple is headed for heartbreak hotel. A source says the latest row is merely a symptom of a bigger problem: "They haven't split up just yet, but things are not good. The fighting is getting worse." One source of contention is apparently Brand's attitude toward his in-laws' religious beliefs. Although Brand is known for his spirituality, he apparently doesn't embrace her preacher pop's radical religious beliefs. Says one insider, "Katy doesn't think Russell respects her parents' Christian beliefs or her friends." Of course, their marriage could revert right back to a teenage dream. Another source adds, "The split may come soon, but they are both so dramatic and volatile, the relationship could become great again."