Lately, things have been tense between Lewis and Fran after she warned her friend and co-star George Harrison away from the Essex boy.
But, despite their fiery exchanges and flying insults, Diags was impressed with Fran after she finally put her feud with Lewis to bed.
During last night's episode of the show, viewers saw Fran and Lewis came face-to-face at the fireworks. Agreeing to disagree, the pair decided to keep their distance from each other and draw a line under their ongoing rows.
In a new video, posted on the official TOWIE website, Diags says he is impressed with his girlfriend for controlling her temper around Lewis, as it is proof she is beginning to work on her anger issues.
"Fran kept her cool with Lewis, I'm very very impressed," Diags said. "That is something for her that is very hard to do - she can flip out on the littlest thing, but she kept calm."
He continued: "I'm really proud of her. It's a start!"
In the episode, Diags was seen stepping in as Lewis and Fran attempted to clear the air. Telling Lewis the situation between him and Fran was ridiculous, Diags told the pair their bickering had to be over and done with.
Speaking about the situation in the new clip, Diags added: "Anyone that says anything hurtful about your girlfriend, you're going to be there to defend them.
"I just wanted to put it to bed. I know I get angry, but I'd rather it be done and they don't speak to each other."
Diags comments come after Fran and Lewis have continuously been arguing in a bitter personal feud.
Stemming from Fran's warning about Lewis to George, the pair have continued to insult each other.
While Fran said she found Lewis to be an "arrogant a***hole", Lewis branded Fran a pug on Twitter - causing Diags to confront him about his comments.
As well as their issues with Lewis, Fran and Diags have had to deal with their own relationship problems too lately.
After finding photos of a girl in her underwear on Diags phone, Fran confronted her boyfriend and the pair found themselves in the middle of an explosive row.
While Fran told Diags he needed to "man up", Diags said she needed to work on her temper as well as her trust issues.
Since then, Fran has spoken out to assure fans she still loves "her James" and is fully aware that they both have issues they need to deal with to make their relationship work.
And, with Diags confronting Lewis and Fran keeping her cool, it sounds like they're already making progress!
TOWIE continues this Sunday 9 November at 10pm on ITVBe.
Reveal is now on Google Plus! Join us here for the latest pictures, fashion and celebrity news!