Trust Issues Over Deleted Messages

My boyfriend deleted messages from his male gym partner. So I (25F) been dating my bf (28M)

for about a year now. things been goo mostly.. We workout together

sometimes, go on small trips, i really tried being the "understanding, supportive gf" type

especially since he told me before how his ex used to be controlling. so I told myself

I won't be that. lately though, he's been spending more time at the gym.

not a big deal, he's serious about fitness and i like that. but few days ago,

i was borrowing his phone to play music while we drove, and i saw a notification from his gym partner

(a guy). when i asked about it, he suddenly grabbed the phone and said