<human>: Condense the text into a few key points

My wife has in the past few months been talking more and more about this guy who works in her office. She has made comments about how he tries to flirt with her, but how it makes her uncomfortable. She says she doesn't want to make a big deal, but she is usually highly confrontational so that alone is unusual. She isn't the sort to try making me jealous, so I don't know why she is saying this to me.   

In the last couple of months she has taken a much greater interest in her appearance, and casually mentioned (while drunk on our way back from a party) that she has been talking with this coworker about our arguments. In the last month she suddenly has reasons to go in on weekends and go back to the office at night. The company does stuff internationally, so it's conceivable that she is telling the truth, but has gone from something that literally never happened to being a couple of times per week.   

She texted me saying that she has a really important project she needs to finish before the holiday and she has to go in tonight. It was a "might have to go in" yesterday to a "have to" today, which suggests to me that she was waiting to make a plan with this guy. We have a young daughter and an infant so I can't follow her or leave the house tonight. There is literally no chance she would confess if I asked her, I am sure most people frown upon the idea of "trying to catch her" but honestly that's the point we're at with trust in our relationship and knowing whether or not she is having an affair is really a way of knowing whether or not it is worth it to keep fighting.  

Is there any reasonable way of finding out what she is up to that does not involve going through her phone or emails? I am okay with the idea of following her, where I am only ever going to find out whether she is cheating, and confess my suspicions either way. Going through her emails or texts feels like a whole other thing though, because I am guaranteeing that I sift through private conversations that aren't mine to read. Does anyone have suggestions?
<bot>: Suspect wife is cheating, don't believe she will confess but don't want to violate her privacy in an effort to find out.