Relationships are alive, they are talking mirrors that give us ongoing feedback. To think that we can force a union denies the inherent spiritual qualities of a relationship. When we recognize this, we understand that unions cannot be forced without great confusion, struggle and despair. I periodically get clients who have paid someone to do a love spell. In reality this doesn't work, you still have to contend with your own problems.
Power comes from within.
The more we hand it over to someone else, the weaker we feel. Love spells may leave you weaker because you've diluted your own power. Intent is very important in any ritual. If the intent is to manipulate, we interfere with an intricate framework, the natural flow of life. Every ritual should be aligned with God's will or Divine Intelligence.