I haven't exactly been in your shoes but I say trust your intuition. Are there conversations flirty? Discussing personal stuff or what? That might be your best clue. However it is a good sign that he hasn't locked his phone. My ex did that when his EA started. Point is you know this man.
I am sure there are others that can give better advice regarding your particular situation. My ex started lying to me 3 years ago and hasn't stopped yet. Keep posting, it helps bring clarity.
kat
Me-53(and learning!) S24, S21, D18, D17 Just keep swimming, Just keep swimming. Dory