This is the best viewing angle for your cuckold.
Place him where you can look into his eyes while your lover spoons you, strokes you – enters you. Your cuckold doesn’t need to see your body yield to the penetration of your lover because he’ll see it in your face and the way you present yourself to your lover to encourage him deeper inside you.
I agree with this suggestion. Another good position is when she straddles over her husband (as in the picture “In The Marital Bed” above) and not he, but her boyfriend enters her from behind. That way, the couple can look at each other and kiss while she enjoys the preferred penis inside her. Doing the same sideways has the advantage that she may stroke her husband with her hand.