They certainly can but there are no guarantees.
Love spells, and indeed all deliberate endeavours, work only because reality is a unified field of infinite consciousness. If anything were truly separate or limited, nothing--not just magic--would happen.
Yes, the trite saying that "With God all things are possible" is the literal truth.
The desired reality exists right here and now but is temporarily invisible due to habitual patterns of consciousness.
In principle, if you could immerse yourself fully in the desired state using any tool to shift consciousness, you would instantly experience it as reality because consciousness is the only reality. However, the powerful addiction to routine perception makes leaps of consciousness uncommon, difficult, or even temporarily impossible.
Instead of attempting a direct shift from one state into another that is considerably, or even radically, different, one chooses to abide in the essence (feeling) of the desired state, i.e. a feeling of calm fulfillment.
THE FEELING IS THE SECRET.
If you could align to the feeling of the wish having already been fulfilled despite the objections of the natural mind, the desire will emerge into your experience in perfect correspondence to your conviction.
The catch? All other realities, infinite in number, also exist simultaneously. In short, your desire does not prevent other states from existing simultaneously and the degree to which you can hold your individual preference without entering into conflict with other ideas--even if they seem opposed--is critical. This is part of the reason why a lot of people suggest letting go and getting on with the rest of it: obsessive tendencies, especially those founded on some unpleasant attachment to perceived loss, usually cause more problems.
Further, your desired reality--even if it could be guaranteed in duality--can take on an infinite variety of forms and paths to those forms. Therefore, predicting how and when the desire manifests is virtually impossible even though aligning to the feeling of calm fulfillment greatly increases your propensity to manifest what you desire.
And still, the desired state in a plethora of forms, exists eternally in the absolute sense of existence even in the face of "conclusive" evidence to the contrary.