We've been best friends for more than 10 years. Our relationship started as a mid school flirt but nothing romantic ever happened after. Of course we each had our own romantic relationships during all these years (more me than her I guess), but nothing really serious happened, and even less in the last few years. We are really close, discuss a lot about our private lives, she hugs me a lot and even sometimes wraps her arm around mine when walking side by side. Recently she complained about people our age going forward in terms of relationships while she is treading. And it made me think that maybe our relationship is part of the problem. Sometimes I feel like she acts a bit as if I was a subtitute boyfriend and like we are too emotionally invested to have a profound romatic relationship with someone but of course romantically unfulfilled as it's friendship. How do I explore this idea further with her to maybe solve our individual romantic struggles?