My boyfriend doesn’t care about it, but he still says that my best friend is just “waiting for his turn with me.”
'Wrong' or 'not wrong' that is 'moral' and I don't think moral means much in a couple (edit: moral is a church thing, or maybe a tribunal one). Moral also puts you at risk of seeing yourself in the eyes of your partner (or them seeing themselves in your eyes) as 'the bad guy', or worse, which certainly will not help solve any doubt or issue you might have. Last, moral can prevent you you from asking yourself the right (and somewhat very simple) question that can help you feel better regarding that 'issue': is it something you're fine with? You both, I mean. To make it clear:
- Would you/Do you care if your boyfriend has a girl best friend with whom he likes to spend as much time as possible, and share everything, even the most personal?
- If that girl best friend existed, would you think she too is waiting for her turn to be with him?
Honestly answering those two questions can help you have a better understanding of what your partner may feel.
Since you wanted to know our personal opinions on the question of (other gender) friendship, here are my 2 cents... in two points:
- My spouse and I are certainly not teenagers anymore as we're both nearing our 60s. We have also been together for close to 30 years and counting. We still meet people of various genders and we both have friends the other is not that happy with. without any issue.
Because we also quickly realized being in a couple should not mean doing everything together, spending all our time together, having the same ideas, desires, and so on. Contrary to what Plato told us, we're not one my spouse and I. We're two different persons that enjoy being together while having many opposing views and tastes. It's just that we value our relationship enough to always be more willing to make things work between us even when it's not easy, than to just part ways each time we don't agree on something ;) - Sincere friendship is rare and precious. It is at least as rare and precious as sincere love. And it certainly is a lot more important than sex, even when it's great.