Why are my needs being ignored?

myself being the non, ive learned a lot from this site, Thank you all for sharing both sides of this.

This relationship has been off and on for 15 plus years.

I knew something was off due to her behavior, but had not educated myself with mental health issues.

Im not going to go into great detail but i just need some insight on these issues and what suggestions any may have.

what happened to my attention, needs,boundaries, respect?

why does it start off great and mutually respectful and then dies?

 why does she not want to talk about my concerns, but wants me  to listen  to all that she has done at work..but never about our relationship and concerns?

i do have the support of her family,,, however id like a starting point from those that have moreso walked in these shoes.