I'd like to ask about the morality of homewrecking: if two people, say B and J, are married, is there anything wrong with a third person, A, actively pursuing B?
It seems to me that A could say: it takes two to tango; everyone has a right to maximise their happiness; one should respect B's autonomy; and I'm not responsible for the consequences of B's actions.
J could reply: but you cause foreseeable suffering by your actions. To which A could respond: I think autonomy and the morality of what actions are permitted should trump the morality of thinking about consequences, but even when applying the morality of consequences: if B stays, then both he and I will be unhappy; if B goes, then it is only you who are unhappy.
What do you think? Is homewrecking clearly morally wrong?
The way you set up the question is quite interesting. While you are right (as J points out), one reason to think that the "home wrecking" is wrong would be foreseeable suffering, but this would seem to be not the strongest reason because (as you point out) the "home wrecking" might actually produce a net gain in happiness even if J suffers quite a bit from the loss. I suggest that the stronger reason for A not to pursue the breakdown of the marriage is that marriage itself consists of mutual promises (vows) between two persons to be steadfast in their loyalty / faith to each other. In most cases, this is probably a vow for life-long fidelity in terms of sexuality -- but also in terms of the primacy of allegiance in a couple constituting a family, even if only two are the family with no children. Assuming that the marriage vow is for life-long fidelity, the third party "A" really is the outsider and is launching an external (intentional?) challenge (J would probably see it as an assault) on the vow...