Been with DP 1.5 years.
He messaged his ex on her birthday. Nothing dodgy, literally just 'happy birthday, what are you up to work wise, hope you're well' etc. She replied, but he didn't reply back, so just one birthday message.
Problem is, he didn't tell me. I saw it on his sent emails whilst looking for some flight details.
He says he didn't think I'd find it (not an excuse), and that I'd get upset by it and he didn't want to deal with the fallout. He said he just wanted to see how she was, and be polite, as she messaged him the previous birthday.
I got upset, not because he messaged her, nor because of the innocent content, but it just felt strange he kept it a secret.
AIBU?