Butterfly and Albatross
The song shows the pain of an albatross personality committed to a butterfly personality. Albatross here corresponds to socially-monogamous personalities, while butterfly corresponds to non-monogamous, or in extreme sense, promiscuous.
The protagonist, who happens to be monogamous, is in a marriage with the butterfly personality. She is pained with his behaviour that she considers, in a denigrating sense, as "loyalty with many". She did not expect this of him when she married him.
She tries to cage her partner, to show him her pain, but realises the futility of trying to cage a butterfly. She can't change his nature. She then frees him to let him be himself, ending the drag of herself as well as her partner. She doesn't respect him. He shouldn't have made a commitment he cannot uphold.
A person, insufficiently aware of his own nature, does no good to anyone by making a commitment that he cannot uphold in the long run.
One should always make minimal commitments in life. We should make commitments only after knowing the nature of ourselves as well as our partner adequately, so as to create a contract that is self-fulfilling in nature, the enforcement of which occurs with minimal effort, and which aligns well with our human emotions, so as to create equitable fulfilment for both partners in the long term.
Making a commitment is like issuing a payment cheque, if it bounces due to insufficient balance, it is dishonoured. When one's cheque is dishonoured, he too wouldn't be considered worthy of honour. One should always issue cheques of cumulative amount less than one's net bank balance.
Promiscuity is not respected in society, and rightly so. It makes us shallow beings, and incapable of making long-term, secure, reliable relationships. It is acceptable as far as it doesn't involve acute pain, betrayal and dishonesty. For emotional needs of butterfly personalities, responsible non-monogamous relationships are worthy solutions. They should be explored on their own merits with open mind and without prejudice. The world doesn't have to be divided between the good ones and the bad ones, but a general and inclusive 'the good enough'.