You have to admit to yourself that your wife is unsatisfied and undersexed! As a man, you simply don't have it in you; you can't bring her to orgasm! It doesn't matter if it's because of your small penis or your lack of stamina. Or if you simply don't have the technique and don't understand what she really needs. It's time you set her free and allow other potent men to fuck her and bring her to orgasm! She's permanently unsatisfied and needs orgasms back in her life! Maybe she's afraid to do it, but I can tell you exactly what's going on and how you can change that! Wife sharing isn't shameful; it can be a true enrichment for your relationship! ;-)