Your gut knows :he's cheating

My boyfriend and I have been together for 6 years . We have one daughter and just bought a house .. But our relationship hasn't always been steady .. Recently he decided to go work for a woman he knew back in college .. And it will only be him and her together working every day . No one else .. He never mentioned her until he annoyed the opportunity.. This job will increase our income tremendously . But since he accepted the job ( not yet leaving his perivous job becz we were waiting to close on the house ) he's been home from work late .. And on days off he has to meet with her to get things in order for the new job .. We agreed to start trying for our second but I feel as if i am forcing him.. Am I crazy ? Is your gut always right ?