Danielle was left heartbroken when Lockie confessed he'd slept with three other women before they were an "official" couple – despite initially denying he'd been unfaithful.
She dumped him but he's been trying to win her back.
On last night's episode of the Essex-based reality show, viewers saw Lockie sending Danielle a beautiful bouquet of flowers and handwritten letter explaining his feelings.
Chatting to the official TOWIE website, Danielle said: "I did get a little upset when he said about not many people can say they're in love with their best friend... It's just horrible. It's such a s**t situation to be in. It's so raw and I don't wish it on any girl ever."
Danielle couldn't read Lockie's letter herself at first, so friend Bobby Cole Norris read it to her.
In the note, Lockie admitted he found it hard to show his emotions and reiterated that he'd never expected to fall in love with Danielle when they began dating.
"I didn't want to let myself have strong feelings for you as it did scare me that you might f**k me off again. I know it's not a good excuse but it's why I slept with those girls," he wrote. "Even when we did make it official I still felt unsure and you made me feel a little bit vulnerable."
Lockie continued to say he now knew he didn't want to be with anyone but Danielle.
"These last few weeks have been so stressful and I'm so sorry this has all been because of my stupid ways. All I want now is for us to wipe the slate clean, start again and have the chance to prove to you I'm the boyfriend you want. I know how good we are together and not many people can say they're in love with their best friend."
But while Lockie's letter made Danielle a bit upset, it seems he hasn't entirely won her back yet.
Later on in the episode, she told her friends that while she knew it had taken him a lot to write the letter, she didn't feel it was enough.
"After that letter all I wanted to do was give him a cuddle, then I thought, 'I have to be strong'."
TOWIE continues Wednesday night on ITV2.
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