Is This Normal For A Relationship?

Ok so I’ve been w my current bf for over 6 months. I have never been happier w anyone & I love him. My friend invited her bf, my ex bf and I to her cottage. I turned her invite down cause I thought it’d be disrespectful & fishy if I went up to my friends cottage for a weekend when my ex bf is there. I told my current bf abt the invite & that I said no to it and he said “ you can go, I trust you, just keep it in your pants.” Idk why I just find it super weird that my bf is okay w me spending a couple nights w my ex bf in a cottage. If it were him asking me if he could do this my instant reaction would be HELL NO. Idk if it’s bad that he’s so comfortable w this. Does he actually trust me this much or does he just not care. I don’t know!!! Btw even tho my bf gave me permission to go i am not. Seriously tho can I have some ladies opinions on this!