Yeah expecting one person to fill every role is unhealthy if even dangerous in relationships. It’s enmeshing and codependency. An unhealthy power dynamic. Plus with sexual intimate relationships they often end in the most traumatic way where ghosting is pretty much expected. At least that is pretty common in our swipe culture and divorce leaving a person in a mess. Meanwhile with friends at least you have a network of friends whom you all fulfill different aspects and they don’t challenge each other. You can still have a sexual relationship with someone but it is less impacting on the whole of the person. Having one piece for the dog and another piece with someone else seems entirely much more healthier dynamic on maintaining a whole. That is after all what the other pieces are doing too, they have other things that fulfill different aspects of themselves. It doesn’t have to come from one and only one other person. That is pretty much how our society is put together too. Everything around us are maintained by multiple people doing multiple jobs.