I think they probably picked up on the fact that in most healthy relationships, partners are able to on an ongoing basis discuss issues and problems without being worried that will mean everything falls down - because they haven't put the relationship on an unrealistic pedestal.
Instead they have built it from solid foundations, with both partners already having emotional maturity, healthy (compatible) boundaries, stable mindsets and well suited communication styles from the start.
If you can't be 100% yourself in a relationship, you won't be 50% of a healthy couple.
That's not to say most people in healthy relationships are perfect - far from it, it's that they have self awareness of their strengths and weaknesses and want to learn and grow - doing that hard work on themselves to be ready for a relationship.
Your relationship sounds like two people with existing issues and conflicting boundaries and communication styles, so when there is a problem instead of communicating it healthily you fear that your relationship will implode so avoid confronting it and instead hide behind the romanticised version of the relationship.
Long term that will become toxic as underlying resentment will grow, more issues will crop up and boundaries will be broken.
Being so reliant on each other for all your needs is impossible to live up to. I understand you say well what am I supposed to do about my needs if I don't have friends etc but that's where having a good therapist comes in.
A good therapist won't let you dismiss the option of leaving on that basis, they will work with you to challenge it and develop tools to start to make friends and have elements of your life outside the relationship. That should be something everyone has, not just people who are potentially splitting up.
I notice you've said you wouldn't ever want another relationship and would be happy with your baby and dog if you split. You need to talk that over with your therapist.
Because it would be so life changing for you to be open to a non perfect (in that you wouldn't put it on such a romanticised pedestal) but genuinely healthy, happy and stable relationship.
At the moment I think you think of love as passion, intensity, dependence and sex. And drama. I used to be like that and was in abusive relationships - us against the world, can't live without each other etc.
Love doesn't have to be like that - you can have passion and emotional connection and amazing sex without the drama and negative intensity. You should never feel your world would come crashing down and you'd hibernate alone if a relationship ended.
It's unhealthy and it actually makes your relationship stand still in time and not grow the roots to remain strong - because you aren't growing as people separately, you are in a status quo together and that often means a cycle of drama because it's what you're used to.
I know this thread might have felt hard for you but you are very, very resistant to being challenged in your thinking and also resistant to hearing things that shine a light on your partners flaws. By resisting those things you're painting yourself to other people as a martyr and (I hate to say it) a mug.
You have more in your locker than that and you aren't tapping into it because this relationship and your cognitive dissonance about the relationship are totally blocking you moving forward in your life, whether you stay together or not.
From what you've said he is clearly not ready, willing or able to do the hard work needed either. I don't think you can work through these issues while you're together.
Remember you're in a relationship based on his credentials not his potential.