Electron-optical phonon interaction is the dominant energy-loss mechanism in low dimensional Ge/SiGe heterostructures and represents a key parameter for the design and realization of electronic and optoelectronic devices based on this material system compatible with the mainstream Si-CMOS technology. Here we investigate the intersubband relaxation dynamics of n-type Ge/SiGe multi-quantum wells with different symmetry and design by means of single-color pump-probe spectroscopy. By comparing the experimental differential transmittance data as a function of the pump-probe delay with numerical calculations based on an energy-balance rate equation model, we could quantify an effective value for the optical phonon deformation potential describing the electron-phonon coupling in 2D Ge-based systems. We found non-radiative relaxation times longer than 20 ps even in samples having intersubband energy separations larger than the optical phonon energy, evidencing the presence of a less effective electron-phonon coupling with respect to what estimated in bulk Ge.