Pete Davidson and Kate Beckinsale. Picture: Bang Showbiz

Kate Beckinsale's relationship with Pete Davidson "ran its course".

The 45-year-old actress began dating the 'Saturday Night Live' star - who, at 25, is 20 years her junior - in January but their "casual" romance has now reportedly "fizzled out", but they remain in contact and plan to stay friends.

A source told E! News: "They still talk and are very friendly."

The 'Widow' actress previously admitted she was "surprised by the interest" in her romance with the comic.

She added: "I've never been in this position before -- never dated anybody who comes with their own bag of mischief.

"It's all quite shocking, and something to get used to. I think if you liked the person less, you would bow out of it. If that were the main thrust of the relationship, there would be a problem. But it's not."

And she felt the attention it was receiving felt a "bit tired".

And Pete previously defended the age gap between them, insisting it shouldn't be a big deal because people didn't question older men dating younger women.

Speaking on 'SNL', he said: "Apparently people have a crazy fascination with our age difference. It doesn't really bother us, but then again I'm new to this. 

"So if you have questions about a relationship with a big age difference, just ask Leonardo DiCaprio, Jason Statham, Michael Douglas, Richard Gere, Jeff Goldblum, Scott Disick, Dane Cook, Derek Jeter, Bruce Willis, Harrison Ford, Tommy Lee, Alec Baldwin, Sean Penn and whoever the president of France is.

"Mel Gibson, Billy Joel, Mick Jagger, Sylvester Stallone, Eddie Murphy, Kelsey Grammer. Larry King, Larry King, Larry King, Rod Stewart and Donald Trump."