How do you maintain close friendships after one person develops feelings?

I’ve noticed this has happened to me more than once, and I honestly never know if I’m handling it correctly.
One situation involved a girl I had been talking to online for almost 2 years. We became really close over time, but in my head it was always friendship. Recently, she admitted she had feelings for me. Looking back, the signs were probably there, but I either missed them or subconsciously ignored them.

My first reaction was honestly panic. I avoided the conversation for a bit and changed the topic because I didn’t know how to respond. Later I felt guilty because opening up emotionally takes courage, so I eventually acknowledged her feelings properly and gently let her down. Thankfully we’re still close friends, but part of me still feels like she may still have feelings and is suppressing them just to keep the friendship alive.

The second time was with a coworker who had just joined our team after college. We got along instantly because we had similar energy and humor. One night she drunk-called me and confessed that she had a crush on me, even though we had never met in person outside work meetings.
The next day, when she was sober, I told her I only saw her platonically and more like a younger sibling. She handled it maturely, apologized, and I reassured her that there was nothing embarrassing about it.

My question is that, If I maintain the friendship like this would it be harder for them to move on. Should I gradually limit the interaction with them so that they can easily move on?