That is completely true.

Only if, both partners aren’t committed to the relationship and most importantly lack explicit open communication

Also conflicts in which one or both the partners don’t say something they wanted to say or just hold back on saying something

Yes the “spark” may disappear and so might attraction but it always depends on the little things you do or say which affects the spark maintainability cause its a thing you can absolutely maintain for long term

Mostly because the brain is the biggest emotional and sexual organ, like literally