Evolution in time (since the start of mass transfer at t_RLOF = 9.62034 × 10⁷ yr) of the primary’s spin angular velocity in units of the orbital velocity, Ω₁/ω (dotted green curve, left axis), for the 5 + 3 M_⊙ system, initial period P_i = 7 d, using the osculating formalism. Panel a): as the primary evolves off the main sequence up to the onset of mass transfer; panel b): during the self-accretion phase; panel c): during the slow mass transfer phase. Panel b) also shows the fraction of ejected material that falls back onto the primary, α_self (solid black curve, left axis), and the ratio of the tidal synchronization timescale to the mass transfer timescale, τ_sync/τ_Ṁ (dashed blue curve, right axis). Note the change in scales along the x-axis in each panel. The top panels indicate the evolution of q = M₁/M₂, and the open red square indicates where q = 1.