Love for another is not a threat to one's being. This would be zero-sum. Love is an expression of your values to another person, and the more you value, the more you are capable of loving. You can love your partner and your child intensely, yes. And the love for a child doesn't threaten your partner's value to you. However, it is more complicated with polysexuality. I've personally been conflicted with finding a proper answer to it, and this is because I believe in mind-body integration as well as the principle of "if it is moral, then it is practical."
If it is hypothetically true that romantic love can be unlimited, and you are metaphysically capable of romantically and sexually loving two or more people, then there is no mind-body dichotomy, even if you're sexually engaged with one person while the other person is not present. I previously believed it was a dichotomy because you're partaking in a physical action that is involving the highest expression of love (sex) with another person other than your partner, even if you sincerely love them both. And this was a zero-sum fallacy, because you can reasonably spend quality time with a friend over another friend due to external circumstances, but it does not decrease the value of their friendship.
I still find it too repulsive, but it can be objectively defended to this extent.
The real issue is the principle of what is moral is also practical. I discussed the ethics of monoamorous polysexuality with my partner and we both concluded that while this is more practical, it is also more immoral than polyamorous polysexuality because you are disintegrating your mind and body---both belong to your primary partner but only the latter can be expressed to others.
11/04/23. Romantic realist.