I (27M) fell in love with a girl (20F), she rejected me and I wanted space, now she want's me to continue our friendship

So basically I said I just wanted space for some time. She took this as that she's never allowed to talk to me again.

Yesterday her lover(26M), which is also a friend of mine, I've known for a long time, came to talk to me and told me this. He also doesn't want to do anything with me until I start being friends with her again, because he thinks he's standing between us.

I tried doing activities with both of them together, but somehow it always makes me miserable to see her happy with someone else.

Next week is a festival where we planned to go together and I lined everything up to see how things are going or in which direction we can move from here. For info: Another girl is also going with us I think the dynamic would change a bit. There's also a lot of other people I know at the festival.

I feel like I should just talk to 20F, but I don't think I will tell her anything she want's to hear. So I don't know if this can improve the situation in any way.