To some degree, YES.
In another way-consider options IMAGINATIVELY.
We tend to only imagine what we think is FEASIBLE-but the truth is that all of the magnificently trivial things (like lightbulbs and internet) that we use every day were inspired by someone imagining the "impossible" and then striving to make it possible and realistic.
So, what seems impossible to you right now-may very well be perfectly possible if you put in the right pieces and parts.
in the case of your examples, it's been proven by a number of us that it IS possible to have a "third" person who becomes a completely integrated part of an already existing family dynamic.
So, it's ok that you aren't there RIGHT NOW. But, that doesn't mean it can't happen.
Instead of considering your future based upon what you think is realistic-try to sit down and imagine what your future would be if you could create it "perfectly".
Then, consider what changes would make that possible-because with
"creative adaptation" (look up the term on google, you should be able to find more info)
You can create something magnificent.
*unrelated to poly example to follow*
My baby sister is about to turn 19. In May she graduated from highschool with a straight A highschool record and is preparing to start college.
At birth, she didn't take her first breath for long enough that the NICU doctor was called. They didn't think she was going to make it.
She stayed purple-from not enough oxygen-for several WEEKS.
She would turn deep purple/blue from lack of oxygen every time she cried for MONTHS.
Her lips continued to turn blue every time she cried for several YEARS.
She didn't walk until she was 2.
She wasn't potty trained until she was 6.
Very quickly after starting school it was surmised that she had learning disabilities and after much testing, the doctors were clear that it was unlikely she'd every mature past a 6-8 year old child emotionally or intellectually.
She's still slow, emotionally she runs 2-3 years behind her peers.
But, my mom was able to enroll her in an awesome private school that worked with her one on one through 8th grade.
Then, I helped homeschool her for highschool.
She did all of the standardized testing required by federal law and she passed all of the testing by our state standards to get a full high school diploma-because she got one on one help in her studies.
We designed her school days around HER learning styles-not giving her the "out" that she was never going to be able to do it-but making sure we found a way for her to do it.
She was always one off in math-one number. If the answer was 8, she always got 7. ALWAYS. So we finally taught her to add 1 to whatever she thought the answer was. It worked-she made it through Algebra 1 and Geometry!
Use your imagination to picture the future you really want-then, figure out what weird things will make it happen-and do them.
"Love As Thou Wilt"