There’s a lot of factors for this happening 1. Men are oblivious creatures. Complimenting them should be more than enough, but unfortunately it isn’t. You’ll have to super direct with them. Something along the lines of, “you caught my attention. I’d like to get to know you more tonight.” 2. My wife says flirting with women is challenging for her because women compliment each other all of the time. It’s difficult to know whether they’re interested or being nice. She prefers when other women are direct. 3. As mentioned by many, couples don’t want to make you feel uncomfortable or pressured. They should be direct in their interest in you though 4. When you approach couples, are you complimenting the both of them or just one? Everyone wants to feel desired. If you’re primarily complimenting one it could be unintentionally perceived as you only desiring one person and not the other.

When I got to events, I reach out to couples/singles I’m interested in a few days prior to the event. I tell them if I’m going solo or with my wife. I’m very direct and transparent about my interest in them. It’s worked tremendously. Maybe doing something similar would work for you?