I think in a situation where both parties have ALL of the following they might be able to maintain a loveless marriage ('marriage in name only =MINO) in peace and maintain a modicum of sanity and 'peace of mind':
- completely honest with each other
- financially equal AND comfortable
- can agree on how to handle family expenses
- equal in 'lack of feeling' for each other (this is very important)
- can agree on their 'non-marital' lifestyle (ie both agree on open marriage or celibacy), AND
- have a big enough home to carve out separate spaces
But honestly, how often do all those circumstances fall in alignment? Almost never. And if they do at the moment of 'agreement', how long will that last? Probably not very long. It's a pipe dream. It usually transpires that one party feels more, is financially dependent, wants sexual freedom, doesn't carry their share of the household drudgery and child responsibilities, etc etc.
Someone may be able to deceive themselves into thinking they are happy, but that's usually the partner in the catbird seat. The partner who feels more, does more, or has less will invariably be unhappy. If someone divorces and is unhappy, at least that's something they can acknowledge and work on, whereas if someone stays in a MINO they must try to convince themselves that they are happy, or else they must confront the question "Why am I really here?". And 'for the children' will not make that person truly happy. They'll just be 'unhappy for a reason'.
And I believe that children can sense a 'lack of love' in their parents just as keenly as they can sense the love that a happily married couple have for each other. So even if a couple can rub along somewhat peacefully in a MINO they are teaching their children that it's just fine to 'settle' for someone they don't love in order to attain the goal of 'marriage and children' rather than to seek a real and meaningful love.
DH and I have been married over 35 years. We've had our good times and our bad times. But our children have always known that through good and bad we have a deep and abiding love for each other. I'm sure that neither of us would have been able to maintain a facade of love in a MINO. Nor would either of us have wanted to.