Sure, relationships do adapt to the resources we put into them. But sorry, I just don't buy that the feelings of love aren't affected by those adaptations. Wouldn't committing more resources into a relationship likely increase the love within? So why wouldn't fewer resources make it more prone to diminish?
I never said it can grow infinitely that way. I never said it can grow infinitely at all. Nor do I think that one should give away all of their resources to anyone.
I know you never meant to go to the extreme Nettle described. But his is one of the many clear illustrations that feelings of love are not proportional to the resources allocated.
Commiting more fully to a relationship
may increase love and intimacy,
but it is not necessarily so. (Actually, imho causality is usually the other way round.)
Taking resources away from a relationship
may result in a diminishing the love and intimacy, but for many people and situations,
it is not necessarily so.
There are certainly situations - perhaps if there has been a little bit of complacency, or even neglect going on - where putting in more effort clearly helps. But sometimes there is even inverse proportionality. As in when two people are a little fed up with each other, and one of them taking on a hobby resulting in less time together leads to renewing the energy of the relationship.
Seeing someone a lot = Loving them a lot (applicable to other resources as well) is a rule of thumb at best. (And my aforementioned friend would argue to death that it's a terrible one ... agreeably, she's somewhat of an exception.) There are obviously upper and lower boundaries for the applicability of this rule, and to some people and situations it will be less applicable than to others.
As for how much it can grow... I don't have an answer. I don't think there is an answer that applies to everyone. Some have large capacities, and some have small. What I do think, is that everyone's capacities can be looked at like a pie graph. We all have our 100%. For some, everyone that fits inside has equal portions, and others have varying. Do you love your husband more than your friend? If so, you just measured love.
I disagree with the pie graph idea. Many people have experienced widening of their capacity when they met someone new.
Or... it depends on what you mean. Actually, I can still describe it with a pie -for simplicity lets talk in terms of time. My free time is a "resource" and can surely be viewed as a pie. Say I give 40% of my free time to my spouse. The rest I spend writing on this forum and doing other bulshit stuff. Yet if my spouse demands more time, I am not willing. I feel like my capacity for relating is full.
Then I meet someone new, and I want to spend time with them. Suddenly I find myself giving 30% of my time to my spouse (let's realistically decrease it a bit) and 30% to the new person. In total, I'm now giving 60% of my free time to relationships instead of 40%. My capacity to relate (express love), in the way I understand it, has increased. Polyamory may be a viable choice for me.
Now, some people don't work that way, and if they meet someone new, they will want to give 20% and 20%, or all 40% to the new person. Polyamory is much harder to them, because they don't experience this increase in their capacity to relate when they meet someone new.
Does this make any sense?