How Should I Handle This Situation?

TLDR
I've been that creator with one sweet tipper paying the bills, and it feels great right up until you realize you're running an undefined service with a single point of failure. My honest take: the fix isn't rationing warmth, it's writing down what you actually sell.
Is he actually getting something for free?
No, and that's the first thing to get straight in your head. This guy tips £50-60 a day, every few days, drip sexting on your schedule. He is not freeloading - he's paying generously for a product that doesn't have a name. That's the real diagnosis here. The problem isn't his behavior or yours, it's that no defined product exists around the attention you're giving. When scope is undefined, it can only drift, and drift always goes one direction: toward more unpaid GFE over time.
So the fix isn't to emotionally ration him or go cold. It's to productize. Write an actual services menu - sexting blocks with minutes and rates, a GFE tier, what "free with sub" includes and what it doesn't. Once the attention has a price tag, friendliness stops being a negotiation you're having with yourself. Your warm persona stays; the policy just makes it consistent. That's also how you protect yourself from the slow creep: unsolicited demands, guilt trips, "you never used to charge for that." Those are your red flags to snap to paid-only contact immediately, without apology.
One thing I'd push back on in your own plan: "I'll keep it going until I have more subs, then explain he needs to pay." Retreating generosity later usually causes more friction than setting a clear, kind structure now. He's already shown he's happy to wait and pay. A calm announcement - "I love chatting with you - going forward my full-attention sexting sessions are £X for Y minutes, here's how to book" - is gratitude-first, not a paywall ambush. He may not love it. He also may not care, because he was already paying above the rate.
What if he's the whole business?
He is right now, and that's the actual emergency - not the boundary question. One person being the majority of your income means your rent depends on one stranger's mood, and no amount of sweetness prevents a tipper from vanishing, deleting, or just having a bad month. Whales are lovely; they are not a strategy.
Treat his tips as seed money, not salary. Skim a buffer off everything he sends - even 30% in a separate pot buys you negotiating power, because the moment you need his money, you can't afford to enforce anything. Then run a boring 30/60/90 plan: keep the FYP funnel going for new subs, actually chase those silent subscribers with a proper custom offer instead of leaving the door vaguely open, and set a gross-income target that doesn't have his name attached. By 90 days you want the Hero Tipper down under half your income. You don't need to fire him - you need enough other income that you can say "sessions are booked here" without your hands shaking.
Meanwhile, keep the persona friendly. Being warm and interested is the job. Knowing exactly what that friendliness includes for free - and what it doesn't - is what makes it sustainable instead of a slow burnout.
Where do your own lines actually sit?
If he showed up tomorrow wanting double the attention for the same tips, would you notice the moment you'd crossed a line - because you wrote it down, or only when it feels bad? And if he vanished this week, what's your plan B income, in numbers, not hopes? When you're ready to grow your live income alongside Fansly, I'd point you toward xlovecam as the better live-cam choice - cam work diversifies in real time and no single viewer owns your rent.