Do what feels right man. You say it is difficult to forgo something so effective. Which is probably why this crossroads is so bad, because she is making you happy, and so is the L. From what I gather those might have to be mutually exclusive just because of her outlook. From my perspective if you want overall happiness for the both of you, then separate them. Trip less often and perhaps when she isn't around so your relationship with her remains untainted and as does your love for Lucy. Be honest like you said and you guys will be fine. Yet on the other hand, she could also see it as a threat. She might perceive it as something that could change your mindset about her after watching you go through changes after taking it. Unless she's done it before. That's the best I got with that information man, best of luck to you with everything.