I see the options more as a progression, not a "pick one". Otherwise you have not exhausted all the possibilities. First, of course, you make it clear how you feel. Then you live with the situation and be patient for a while. If you otherwise have a good relationship, it doesn't make sense to me to just go for divorce, in which case you've automatically given up all other options. Anybody can just divorce and move on -- crude and blunt and guarantees you won't be continuing to "deal" with the problem.
So before divorcing, you might suggest an open marriage, which can mean a great variety of things with different rules for different people. Newt Gingrich was too harshly criticized for this in my opinion by his ex-wife, who appeared to make him sound like a raging pervert for suggesting such a humiliating thing. We just don't really know the circumstances of his marriage so we can't say any more. But I can certainly see situations where such a suggestion is entirely reasonable if the alternative is simply divorce.
Open relationships are happening more than people think. Therapists claim they are rarely work, but that's because they only see the people who end up in therapy when they don't work. Otherwise people have no incentive to advertise them to the world.
