What Nayes said.
My first one-sided monogamous relationship was when I was a total newbie beginner, with a very beautiful girl I was in love with. At the time I was basically just repeating lines from a coach of mine and figured there was no way she would tolerate it, and no way it was going to work. Except it did.
I had a decent job then but negative net worth. With later one-sided relationships I was jobless and broke.
I will say you learn more about women from succeeding with things you think will never work than from just about anything else you could do.
When 'impossible' stuff works, you end up in a situation where your mind is just continually blown... until you come out of it with a completely different perspective on the thing than what you had going in.
That said, my first one I was still very young, and very irresponsible, and I did a lot of damage. She was okay in the end, but I really put her through a wringer, and felt quite bad for it. It was the biggest relief in the world for me to see her marry a very high quality guy after me... made me feel that okay, I didn't totally wreck her, she bounced back in a great way.
If you run this kind of relationship, you really have to be super careful about the frames you are setting, not just verbally, but also implicitly. Very easy to do a lot of damage if you're too cavalier about things.