Annie Murphy is a gem, able to show the slightest nuances of pain and joy in her expressions in a way that pulls your heart straight out of your chest. But, to me the weak link in this show is Eric Petersen as Kevin. He is so over-the-top in his delivery (even for someone who is supposed to be in a typical sitcom), and so odd looking that it's impossible to imagine Allison would have ever even gone on a single date with him....much less married him.
The show functions better in my mind if I just imagine the role of Kevin being played by Kevin James. Since his show "Kevin Can Wait" served as the inspiration for this show, it makes sense to me that the lines are written for his style of delivery. Shame that he doesn't just step into the role! The show would be much stronger for it.