It's only been three months since we first learned that Kourtney Kardashian and Travis Barker are dating.

But it makes sense that the relationship is progressing at breakneck speed.

After all, Kourtney and Travis have been friends for years, and they're both in their forties.

They know each other; they know what they want, and it seems they're not afraid of going after it.

So don't be surprised if Kourtney and Travis tie the knot in the very near future.

“Marriage is almost certain," a source close to the situation tells Life & Style.

“Her sisters say they’ve never seen Kourtney this crazy in love,” the insider continues.

“Kris [Jenner] is ecstatic that her oldest daughter is this happy … It’s an exciting time for Kourtney, and no one deserves it more than her.” 

And it seems that Kourtney and Travis want the whole world to know just how ecstatic they are.

Instagram users have dubbed them "America's horniest couple" as a result of their non-stop PDA pics.

And friends say it's not just for show -- these two are really that into each other.

“Kourtney and Travis are doing absolutely nothing to squelch the rumors that they’ll be getting married. In fact, it seems that all their actions are pointing in that direction,” the insider adds.

“It’s no secret that they’re in love and enjoying a red-hot, sexually-charged romance."

Fans have been skeptical about marriage rumors, as Kourtney was with Scott Disick for over a decade, and the two of them never felt the need to get hitched.

But sources say Kourtney's feelings for Travis are unlike anything she's experienced previously.

“Kourtney has never been this infatuated or in your face about a guy before,” notes the insider.

“Travis has brought something out in her that has completely freed her," the source continues.

"Her guard is down when she’s with him and she doesn’t care what anyone thinks … This is Kourtney’s time to enjoy herself and she’s taking full advantage of it.”

It sounds like everything is going as well as can be expected for Kourtney and Travis.

So we guess it should come as no surprise that some jealous exes have entered the chat.

Insiders say Scott Disick has been distancing himself from Kourtney as a result of her relationship with Travis.

“It's uncomfortable for Scott to see Kourtney in a serious relationship, although he knew this day would come,” one insider tells E! News.

“Of course they are still cordial when it comes to the kids, but they aren't hanging out as much or doing things as a family. The communication has become strictly about the kids.”

That's not really fair of course, as Scott is dating Amelia Hamlin, and he's been involved in several relationships in the years since he and Kourtney broke up.

But hey, these matters are rarely governed by logic.

Case in point, Younes Bendjima -- who dated Kourtney for a few months several years ago -- is apparently also pissed about how happy she is with Travis.

“Shamelessness has become so normal in today’s society that modesty has become strange,” he tweeted and deleted after Kourtney posted a sultry photo of herself and Travis.

It's a shame that there are people in Kourtney's life who are trying to pour cold water on her hot romance.

Fortunately, it doesn't seem like she'll be allowing any envious outsiders to interfere with her happiness.

And we're sure Scott will get an invitation to the wedding ... whether he wants one or not.