Firefoxx,
There are a few reasons why a girl gets bored in a relationship. The main ones are:
1) The sex is bad / boring
2) She knows you won't leave
3) All intrigue about you is lost
The first one is easy to address. There's a ton of useful info if you search in the "Sex" category. I'd start here:
https://www.girlschase.com/content/make- ... es-or-less
Try something new like some light bondage, costumes etc.
The 2nd and 3rd are things you haven't handled correctly up til now. If she knows for a fact that you won't leave her, then you are more invested and she will become bored with you cause there is no uncertainty. I'd recommend making her a little jealous. I don't usually like manipulative tactics such as this, but if you both profit from it, then no harm done. The key here is a
little jealousy. Do not overdo it! Here's a good article on it:
https://www.girlschase.com/content/makin ... -and-donts
This article isn't really written for those already in a relationship, but it will still work if you follow the four steps at the end.
Now, if you've killed all intrigue about yourself by divulging everything, then it's time to do something spontaneous. I won't dive into this too much. One example would be a last minute short road trip someplace cool.
No guarantees any of this will work. The trick is not to allow your girl to become bored. Once she's here...well, it takes a lot more work to get her interested again.
Best of luck,
-Doc