I came out of Defenders wanting Foggy and Karen to give each other a little happiness in the months that will no doubt elapse before Daredevil's third season. They can fall in love while seeing each other through the grieving process, or later. Romantic fluff tinged with sadness, Foggy learning Karen's secrets and taking them a bit better than he took Matt's (though likely not without some angst), and if Fisk comes after Foggy, well, Karen's lost one man she loved to the shadow elite. She'll be damned if she loses another
Feel free to turn it into a threesome on Matt's return, but the focus should be Foggy and Karen, and what they mean to each other.