You express yourself well. Could put those things under the microscope to see if articulating them all the way out suggests a solution.
I'm afraid some guy/girl might come along and attempt to compete with me. That's honestly my biggest fear.
Ok. They try to compete with you. You choose to NOT compete. She would choose... what? Egg on competition? Tell them to cut it out, that is not respectful to her other partner (you)? What?
In what way could it play out so it is a "scary feeling" way? Where she DOESN'T say anything? Is that part of it?
In what way could it play out so you can move past it? What behavior do you do? She does?
I fear that she'll want to fall in love with someone else and I will part of this triangle. Not to say that I have anything against the practice, but it's just not how I want to live my life. I don't want to have doubts about our life, because I see her as my life partner, and I don't regret any instance that we have had.
So this is a hard limit for you? What open relationship model do you currently share with her? You are willing to be in a 1a shape open model relationship?
A 1C? But NOT 2 anythings? This would be a dealbreaker for you?
You are allowed to have your wants, needs, and limits be whatever they are. Just state them clearly to your partner so you understand each other. That could help reduce fears. Maybe you could both read that article together and discuss?
I have told her that I will allow it, and we have established our rules which is very reassuring, but I just need a community to help me understand and chat with from time to time. Given that we are just about to make a huge commitment to one another by buying a home, I just want to make sure we are both happy with one another and aren't going to be broken down because of this down the road. I don't want to let it happen, but at this point, I'm just afraid of the worst case scenarios.. They always seem to creep their way in.
Are you saying you are doing something you are NOT really willing to do?
Or are you saying you are willing to try it on, but worried/scared because the "new normal" feels weird until it becomes "old normal" and you don't have enough confidence in the couple's ability to handle things as they come up yet because it is all too new?
Have you covered pitfalls? Jealousy?
And go there in the house buying committment.
"Ok, we bought a house together. Now we break up. What do we do about the house then?"
Better to have that plan and not need it than find yourselves there without a paddle. Take the bull by the horns. All of them. Talk honestly to your partner.
It is not possible (nor should you try) to predict everything Life could throw your way. But you could pin down the top 5 on your mind, and focus on HOW to weather whatever else comes along together. Not the WHAT happens. But HOW. How you will do your couple conflict resolution, HOW you agree to treat each other in times of good emotional weather and in times of bad emotional weather so that you can both weather whatever it is out together.