Orlando Bloom Says Romance with Katy Perry's Hard, Kinda Like His Abs

Orlando Bloom's admitting he and Katy Perry have a tough time keeping the romance going in their relationship -- but it definitely isn't for lack of physical beauty, which is crystal clear in some new photos.

Orlando's leaving very little to the imagination ... showing off his abs and more, appropriately, for the new issue of Flaunt. Once you get past the images -- if you can -- he also spoke to the magazine about his fiancée Katy.

Far from gushing about their relationship, Orlando said, "Sometimes things are really, really, really, challenging. I won’t lie. We definitely battle with our emotions and creativity."

Sounds like their rough patches center around work, and the fact their careers are very different. As Orlando puts it, "We’re in two very different pools. Her pool is not a pool that I necessarily understand, and I think my pool is not a pool that she necessarily understands."

The actor's currently starring in the Prime series "Carnival Row" with Cara Delevingne ... and Katy's juggling her "American Idol" judge gig with her Las Vegas residency.

The couple has a 2-year-old daughter, Daisy, and Orlando added, "There's definitely never a dull moment" -- but also made it clear both he and Katy still feel blessed they have each other.