Re: Should I be worried?
I am not ready to jump to the conclusion she is boinking the personal trainer. Staying vigilant but not paranoid would be my advice in terms of infidelity.
At this time I would suggest you attack the relationship issues rather than question her. Don't ask her what she is doing every night, don't complain about her ditzy (****ty?) young female friends. Instead, tell her you want to spend more time together with her. Lead the relationship by planning things together. Tell her you feel things slipping a bit because you are both getting so busy, and you want to reconnect with her. Make it a positive conversation with her, not a nagging or complaining experience. Ask her what she would like more of or less of in the relationship.
If she is having a bit of a mid life crisis as 30 approaches, being positive with her is a better approach than *****ing at her. But still keep your eyes open. I think it a red flag that her previously close friends are saying things to you about her behavior.