Exploring the Limits of Non-Monogamy Tonight

I'm in an open relationship with my partner Sarah. We both agree on the importance of honesty and communication to keep things healthy, but sometimes it gets complicated when exploring new kinks or just plain old physical desires. Last night, I had a date with Alex, whom I've only met twice before this week's arrangement. To be honest, everything about Alex’s body was a turn-on: the way his cock stood straight up when we hugged in greeting, how he rolled down his condom and lubed himself up, making me anticipate every inch of him sliding inside me. We took turns being on top, experimenting with different angles and speeds until I could feel the pressure building up in my balls, knowing it wouldn't be long before I erupted into a mess of cum all over Alex's hand. But then came the part where we both wanted to tie each other up for some light bondage play. That was when things got tricky. I'm still learning what feels okay and what crosses lines in terms of consent, especially since I've only met Alex a few times. Afterward, there was this nagging worry about whether our chemistry had overshadowed proper communication. Am I doing something wrong or is this just part of the fun with non-monogamous exploration? Any advice from those experienced with the ropes and rules would be greatly appreciated.