In standard text books about Superconductivity like "Buckel" one learns that two fermionic electrons (each spin s=1/2) couple and form a boson with total spin of S=0, which is a singlet state (the spins are anti-parallel).
Is there anything preventing them from forming a triplet state S=1 (the spins are parallel)?
Is it related to symmetry considerations?
What would be the consequences of a S=1 state?