We've just updated the way your Contacts link to other Contacts (spouse, partner, kids, etc.). You can now define the "Relationship" between Doug and Kasey (husband and wife).
HOW TO CREATE A RELATIONSHIP
In the sidebar, click on Contacts
Select the Client you want to add an alternate contact for
Select the Edit button in the top right
Scroll to Add Relationship and click. Select the Client in the dialog that appears
If you do not have the Client already saved, you can create one from this dialog you can select New Client
Specify the Label for this Client (e.g. Spouse)
Optionally specify a Reverse Label which describes the relationship in the other direction. For example the label of "Spouse" could apply for both Clients but the labels of "Husband" and "Wife" are direction-specific.
Click Save
Repeat for as many relationships you want to add for this Client
Now anytime you view this contact, Relationships will appear, and be clickable: