It sounds like this just wasn't meant to be... It's odd that she got involved with you deeply, and then pulled back. She sounds less into you than she first was, and she doesn't have the courage to tell you, so she's letting her actions tell you.
And if you really want a wife of your own, you're jealous of "what they have," 2 people, a mono relationship, it sounds to me like you're just torturing yourself.
It would be nice if you could make a respectful clean break. But the way humans are is, if you try and break up, she might then come running back. Only to go back to her old ignoring behaviors a short time later.
I think she's being rather clueless and self involved. Not buying your movie ticket after you bought her dinner, sheesh.
Love withers under constraint; its very essence is liberty. It is compatible neither with envy, jealousy or fear. It is there most pure, perfect and unlimited when its votaries live in confidence, equality and unreserve. -- Shelley
Mags (poly, F, 60) loving miss pixi (poly, F, 38) since January 2009, living together since 2013
also loving Punk (monogamish, 42, M) since Oct 2015
"Master," (mono, 34), miss pixi's Dom for 2 years