I'm going to have to disagree and say there's some nuance to this. Friendships or relationships in general are 50/50 and communication is an important aspect. They're always going to go down a certain path good or bad. If someone decides to share feelings like that which make another uncomfortable such as that then yes that maybe the outcome. However, expecting that person to just sit there, be miserable around someone that doesn't hold the same feelings and to just shut up about it so the other person doesn't feel bad is not a way to go about it. Keep in mind what happens afterwards determines it. Does this person decide to communicate with you afterwards they don't hold the same feelings and you work it out? Possibly ending it? If so then fine. If its immature behavior afterwards? Then...I can't say the same.

To add to my example I did do this. But this was due to the fact that I had no idea where the relationship was heading. This person would come on strong, say a lot of questionable actions, and it was questionable due to the pace of it. Trying to film me without me knowing, always asking where I was to the point of panicking, and having her cousin trying to take photos of me for her. There were a lot of confusing things going on and I began to question where the relationship was heading depsite her having a boyfriend. At one point she just bluntly said "i dont have a mans" right in front of me which added more confusion. I had feelings for them that developed because of these behaviors. Basically game playing.

I later on confessed because it began to the point where the confusion was stressful. They never communicated and decided to say yes to hanging out with me then decided to just claim they didn't understand. After apologizing they still kept continuing immature behavior and saying things that were antagonistic or being passive aggressive because I just wanted space. I ended up having to cut her off because she just continued to not respect boundaries which was a common pattern before and after I confessed.

So to put it there. It's dependent on the situation. Some people will get signs and will ask. Thats going to be a thing. It's just dependent on how either responds is the main case. You say it's selfish because the person who confessed doesn't respect their friends feelings. However if the friend decides to act an immature manner afterwards and doesn't communicate then maybe the person who confessed is in the right to just cut ties after all.