How do I keep him?

So... there's this guy... He and I have been on and off talking for several months, and are kinda in the situationship phase right now. I really like him, I can honestly say I've never liked someone this much- or this way before. Things had been going well... but then one of my lovely best friends got involved. She's an amazing friend and person, however she's never been in a romantic relationship, and has a fear/ belief that she never will be. Due to this, she gets jealous of the fact that I have 'someone', and whenever she gets the chance jumps in and starts flirting with him. She's even asked him on a date. None of this would really be an issue, except for two small details: 1. she has admitted that she likes him. (also wouldn't be a major deal, except for the fact that she's kinda EVERYTHING. the girl a guy dreams about... why would he stay with me when she's an option?) 2. His and my relationship has gone from a solid 50/50 effort to what feels like I'm doing a lot of the work ( I have to initiate text conversations now, etc. ) I say this with respect. I love them both! I don't want any of this to come across as rude to either party, I'm just worried about where our relationship is headed, and how to keep him. He's my best friend... I don't feel like I have to change for him. I can be myself around him. I don't need to change for him, but I want to be a better person because of him. How to I keep our relationship in a healthy place?

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+1 y
this is also highschool drama 😂 just to add, but he just seems to act differently when she's around.
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+1 y
also, just to add, the *50/50 is how I like it- equal effort from both parties.
How do I keep him?
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