How is love a destructive force throughout Macbeth?
Ambition is the most destructive force in the play. Macbeth shows love and respect towards his king and towards his friend Banquo. But this love is not enough to override his own ambition. Macduff, Donalbain, and Malcolm love the king. They temporarily exile themselves in England but this is in order to get help and to form a strategy to overthrow Macbeth. So, in this case, their love for Duncan and Scotland leads to eventual redemption.
If there is an example of love leading to destruction, it is the love between Macbeth and Lady Macbeth. However, over the course of the play, that love transforms into ambition. Between the two of them, each feeds off of the other's ambition. Ambition is reciprocated in this way, in the way that their love for each other used to function. If the original basis of Macbeth's and Lady Macbeth's relationship is/was love, then we can say that this basis served as a foundation upon which they built a relationship of ambition. In other words, ambition supplanted love. But they used their bond in order to encourage each other to continue the quest for more power. In fact, she is the only one that Macbeth stays loyal to. Any other character is at least a potential threat to Macbeth.
So, love works indirectly as a foundation of their relationship that leads to destruction. It is not the love itself that leads to destruction. It is the mutual ambition that springs from that relationship that leads to Lady Macbeth's and Macbeth's destruction.