The Bachelor Nation is still having nightmares about the disturbing texts that Colton Underwood sent to Cassie Randolph.

Now, a report explains why Colton may have gone off the deep end and turned from amicable ex to alleged stalker.

According to what an inside source tells In Touch Weekly, Cassie and Colton's split stemmed from Cassie making some hard realizations.

Before they broke up in May, the insider says that she realized that Colton "was not the guy for her."

The source adds that Colton "just couldn't handle her breaking up with him."

Apparently, Colton was quick to point the finger at outside forces when it came to identifying the cause of the split.

 “He blamed the show, the producers, host Chris Harrison," the insider details.

The source goes on to say that Colton assigned blame to "everyone but himself [for their relationship ending].” 

“Colton admits he had some issues," the insider shares.

"But," the source adds, "that shouldn’t have affected the way he treated Cassie.”

And yet it seems that, according to Cassie, Colton's issues have not only impacted his behavior towards her, but caused him to cross into criminal behavior.

On September 11, Cassie filed for a restraining order against her ex. That protective order was then granted.

Colton must remain at least 100 yards away from Cassie, her home, her vehicle, and her workplace at all times.

This is a short-term, emergency protective order -- which will remain in effect until October 6, when there will be a hearing on the matter.

Within the court documents, Cassie accused Colton of harassing her.

He allegedly bombarded her with unsettling and even menacing text messages.

Worse, he is said to have shown up at her home and at her parents' home without an invitation.

Cassie reported that Colton apparently became fixated on the idea that she was seeing an ex-boyfriend.

Worst of all, however, she accuses him of planting a tracking device on her car.

That is a favored tool of stalkers and we can only imagine her terror upon discovering such a device -- or what red flags must have led her to look for one.

A rep for Colton Underwood has responded.

“As this is a legal matter," the rep reports, "we cannot provide any comment at this time.”

This could mean that the rep does not want to interfere with Colton's legal battle ... or that the rep has no idea what to say and felt that no comment was the best option.

When the couple first split, things seemed amicable, with the two having only positive statements to make about each other -- in public, at least.

In fact, for a time this summer, the two were said to be collaborating on a new reality gig about their post-breakup lives.

Despite being in production all summer, the two have reportedly pulled out of that arrangement. It is unclear what, if anything, will come of their months of hard work.

Tracking devices are favored tools of stalkers, abusive partners, and even toxic and controlling parents.

Victims who have been tracked begin to feel both powerless and paranoid, wondering how their ex always knows what they have done and where they have been.

It is not just a device to learn someone's habits -- it allows a jilted ex, a toxic boyfriend, or anyone else to wage psychological warfare against their victim.

If Cassie's allegations about Colton's behavior are true, this is deeply heartbreaking.

People with unusual stories, who get wrapped up in an almost unbelievable amount of emotion when it comes to relationships, can make for very entertaining television.

But people don't always show their worst sides on camera. When puppy love turns into obsession, things can get dangerous and scary.