My S.O. Has been living in this house for over 15 years, and never had anything like this happen.

Okay - fair enough .... I would keep track of date & time: IE: Monday - 3:00PM and where or what room(s) and what is the weather. Hot, Cold, Rain, Dry, Cloudy sort of thing.

The date - time ... if there is a pattern will help you see this.

Weather is good to have too ...

Also what was going on -- Dinner, Lunch, Breakfast, TV show and such.

What you want to do is find any form of patterns that bring this about.

A theory that I just thought of (creative aren't I) that a haunting could be created by introducing an object into a location with another object that alone were not considered haunted. The best example I can think of to use is two magnets. Two magnets are either attracted to each other or repelled from each other just because one is turned a certain way. But if they are aligned just right then they rush to each other and stick together. So what if a haunting can be like this. Just two seemingly random objects put together could be like those two magnets. It might be impossible to prove and even more difficult to explain. Matter of fact, it's really starting to sound impossible to me after I've been thinking about this for 30 minutes.

My S.O. Has been living in this house for over 15 years, and never had anything like this happen.

Interesting.

I was just a strong scent of men's cologne. We have no neighbors, so it couldn't have been that. Also, there is only one male living in the house and he never wears the stuff.

I will throw out one possibilty:

Did you buy/rent the house from another owner?

IF, 'yes' - easily there could have been the scent of something like inscense or other scents - that was covered up with paint and/or just enough heat - cold - heat ... finally brought it 'out'.

Paint covers a mulitude of 'sins' - but eventually time will bring them out.

But this is just one possible answer.

In a house that has absolutely no paranormal history (that you know of), can it suddenly become haunted?

If it can, any theories on why this might happen?

I've heard about a lot of types of hauntings, ie. residual and active, but I've never heard of a sudden haunting. I'm not talking about a house that someone just moved into and a few months later activity kicks up. I'm talking about a house that you have lived in for years suddenly appearing haunted.

Has anyone heard of or experienced this?

Well first off - what exactly is going on? As specific as you can be.

Right now - I know a few PI-Groups that have had an influx of calls ... why? The homes are going through climate change from the harsh cold winter to the home's warming up and creaks, doors, windows, and such... One even had a bee hive become active. But it was echoing through the vents. Talk about a 'creepy sound'.

So ... specifics would be helpful as to what is 'going on'.

No antiques to speak of. But I hadn't thought of that. It's a very interesting theory.

I'm on the same page as everyone else. It could just be poltergeist(aka self imposed activity) or perhaps someone in your house picked up a hitchhiker. It's happened to me before.

Depends on the activity. You could be experiencing poltergeist-like phenomenon which I'm sure as you know is person related. Or, just a theory, if a person is an unaware medium they could inadvertantly wake something that is associated to the land. And finally, have you bought any antiques? Sometimes spirits will become attached to an item and follow it where ever it goes.

No antiques to speak of. But I hadn't thought of that. It's a very interesting theory.

In a house that has absolutely no paranormal history (that you know of), can it suddenly become haunted?

If it can, any theories on why this might happen?

I've heard about a lot of types of hauntings, ie. residual and active, but I've never heard of a sudden haunting. I'm not talking about a house that someone just moved into and a few months later activity kicks up. I'm talking about a house that you have lived in for years suddenly appearing haunted.

Has anyone heard of or experienced this?

Depends on the activity. You could be experiencing poltergeist-like phenomenon which I'm sure as you know is person related. Or, just a theory, if a person is an unaware medium they could inadvertantly wake something that is associated to the land. And finally, have you bought any antiques? Sometimes spirits will become attached to an item and follow it where ever it goes.

If it can, any theories on why this might happen?

I've heard about a lot of types of hauntings, ie. residual and active, but I've never heard of a sudden haunting. I'm not talking about a house that someone just moved into and a few months later activity kicks up. I'm talking about a house that you have lived in for years suddenly appearing haunted.

Has anyone heard of or experienced this?