Kate Beckinsale and Len Wiseman: Marriage on the Rocks

Kate Beckinsale's husband has been hitting the town like a very single guy over the last month ... a single guy out with a very young model.

42-year-old Len Wiseman has been spotted out -- sans wedding ring -- with 24-year-old CJ Franco. They were out Tuesday night at The Nice Guy, partied until 2 AM and left together.

It's the third time we've seen Len out with CJ, as 42-year-old Kate is ensconced in Prague shooting "Underworld 5."

Kate and Len married in 2004, but it sure seems the marriage has come to a screeching halt.

We reached out to Kate's people but mum's the word.