Fast forward to October 2016, wife drops the I love you but not in love with you. She was disappointed that I would not spend time at home and work too much, my reasoning was to make up for income that she was not earning anymore as she was a stay at home mother. I begged and pleaded her not to end things, was giving her some space and at the same time changed my ways. I started being more active in the baby's life, we would go out more as a family and i would not prioritize work. Things began to get good again, so it seemed. We went on an anniversary trip in Feb 2017 and a family vacation for our daughters birthday in September. All things seemed to be better, we didn't have as much intimacy as i would like but i put it off as it being due to both of us working and having a child would not always allow for it. She dropped this last bomb on me on FEb 28,2018. Said she loves me but not in love with me, she tried to make it work for a long time but she has not been happy since October 2016.
Hello and welcome to the forums! Just to echo what Steve and Artista said, chances of an affair are quite high. It's pretty common for a WAS to make their spouse Plan B (IE, doesn't want to get divorced, but doesn't want to live with you either) while they pursue the A and try to decide how serious they want to get with the affair partner. Have you read DR yet? If not get it and read it over and over again, it's your roadmap and our advice here dovetails with it.
Based on the above paragraph your W is a full-blown, two-feet-out-the-door WAS. DO NOT try to pursue her, it'll just make you look desperate and needy (VERY unattractive). Work on yourself. Settle in, this is a marathon. Good luck!