I think it depends a lot on firstly your own self-esteem, expectations and personal boundaries and, secondly, what sort of relationshp you have with your partner.
It's interesting to me Horatia that you separate your sexual relationship with your dh from the rest of it - friendship, emotional, financial, etc.
For me it is all one package with love, trust, respect and intimacy in all areas. It seems to me that if you are ok with your dh sleeping with other women, then you actually have an 'open marriage' and that's absolutely fine of course, if that's what you both want.
My relationship is very different and my dh knows that if he cheated on me I would be devastated, I would lose all trust in him, I would lose all respect for him and I would not want to be intimate with him. I know that he feels the same way. It would absolutely be a deal breaker for both of us.
The main reason it would fall apart would not be the actual physical 30 minutes of touching someone else's body and poking around with a penis, it would be the lies. The planning, the sneaking, the secret messaging, the covering up, the not caring about me, the risking losing it all, the total selfishness and lack of respect for our relationship.
But we have a very good relationship and if we didn't perhaps I wouldn't care so much.