I'm not an ESTJ but someone has to be honest with you. You seem like a nice guy but there are major issues with your ways of thinking. Being "loyal" and "committed" does not entitle you to a relationship with her.
In my opinion, you are extremely infatuated with this woman. I can understand where you're coming from and I don't deny that you care about her but you're romanticizing her and bordering on nice guy territory (see: https://www.urbandictionary.com/defi...Guy%20Syndrome).
Firstly, I want to point out that bullshit you said about "I honestly believe I can love her better than anyone else." Please never say this again. That is not for you to decide and she deserves better than to be treated like just an object of your desire. You are not the first person to ever love or pine after someone, so get over yourself. Real love is not bought by gifts and being a shoulder to cry on whilst secretly hoping for more. There's nothing wrong with having feelings for a friend- but making such statements even when she has specifically said she does not want a relationship with you is disrespectful IMO and I'm sure she knows what she wants/needs better than you do. She said herself she does not see a relationship with you working out and you can't just force it or jump through hoops trying to make sense of it. She does not want a relationship with you. Full stop.
The quotes:andI don't mind if she settles with me, as I know I'm willing to put in the time and effort to make it work"I'm hoping eventually, my loyalty and devotion might wear her down."
is more evidence of infatuation. If you really loved her you would want her to find someone who brings out the best in her, not want her to settle with you because it's unlikely either of you will be happy that way. You don't get a relationship by telling yourself you've been XYZ so if you continue doing it she should relent and give in to you. I get the desire and desperation to have someone but that's infatuation.
Also marriage pacts don't mean anything. I've made several of these with male friends (jeez, what a slut!) because we were both too scared to be lonely. That doesn't mean anything other than you're her back up option.
My suggestion? Cool down with these fantasies because you're only going to get hurt. People and relationships are not perfect so stop putting them on a pedestal. Focus your energy into something (not someone) else.