Seeing your wife's pussy accept, grip and love someone's else's cock and it finishing inside of her. It's always so wonderful to see how eager a wife/gf is to suck off or fuck someone else. This is what makes being locked in permanent chastity worth it.
I'm sorry you feel that way man. I tell new couples who get into this that they should probably have several long conversations before jumping into it. In addition to attending swinger clubs to gain feedback and maybe spectate on the lifestyle members. I hope you guys are still together and doing ok relationship wise.