In all relationships, the depth of the relationship is decided by the party that wants it shallower. If A and B are in a relationship, A wants it to be a deep, intimate relationship while B wants it to remain shallow, it will, per force, have to remain shallow or break off, because B will not make the personal investment needed to deepen the relationship. A can then choose to sustain the relationship at that shallow level or break off.
In families, romantic relationships, and even business relationships, this is true.
The thing with this is, that only one person makes the decision to keep a relationship shallow, but both parties pay the price. Most long term relationships are like good eggs, they must either hatch (mature into something deeper) or go bad (break off).
Over a long enough period, keeping a relationship shallow hurts both parties because there is, nonetheless, a human need for a deep connection. This is more pronounced in romantic relationships, because we are only allowed one romantic partner at a time. But even among siblings or with parents, there is an inherent need to have a deep relationship. If that need is frustrated by the current relationship, one must look elsewhere (but there is only one sibling/ parent!) or live with the feeling of lack of fulfillment.
It is this lack of fulfillment, this constant feeling that we are living sub optimal lives, that fills us with an inexplicable void. Its inexplicable because we don't understand that we are living at a layer that is not in sync with our needs.
How, then, does one deal with this? If so few people want to invest in deep relationships, whether at home (even parenting has become checklist based and transactional), or in friendships, then how does one find the deep connection that one seeks?
A simple, but not so practical solution is to not be the person who holds up the depth in a relationship. You may not realise it right now, but you are going to need that depth. One day, you will be fifty, and friendless. Think of this as investing in a pension fund. You don't see the returns until you retire. Then, you get them when you need them the most.
I have also found it to be true in the work sphere. Long term work relationships based on mutual respect. Long term vendor relationships mean that our cost of procurement goes down. Long term client relationships mean that our cost of selling is low, and we can give the client a better deal.
In fact, Indian businesses typically demonstrate very long term employment and vendor-client relationships.