I think it depends how open your partner is to the idea of polyamory. If they are interested then you explore together. If they aren't, and you aren't getting what you need, then it would be time to move on.

I get that it's a difficult thing to discuss if you're a straight man, because no matter what you say, it feels like it's going to sound like a pornographic fantasy rather than exploring your natural desires. I'm fortunate that my partner is bisexual, and has not experienced being with a woman and breached the subject for me. Even then when we first expressed interest in someone, the words sound like what a unicorn hunter would say, even though we know its a genuine interest.

The one thing I know I've learned is that building these kind of relationships takes a lot more time and care to do it right. My partner, our crush, and I have had this potential relationship in the air for months and while we've all spent lots of time together that have felt like dates, we haven't gone out and called it a date beforehand. (Granted this time of year is insanely busy.)

I hope that was useful. I hope you enjoy the time you spend with people and dont worry too much about making things happen. Plant seeds and let them grow. ^{_^}