Why am I getting so frustrated playing tennis?

Does anyone have any advice on how to not get frustrated while playing tennis?

I'm just an amateur player and play for fun. I like tournaments and competition but I know I'm not a 'good' player and that's okay. The rating im talking about is between 7.0 - 7.5 (womans and mixed).

However, everytime I have a match (fun or serious) and I think I'm not playing well, making a lot of errors, I get so frustrated with myself. It really changes my mood during the match and I don't like it. Every time I try to tell myself to stay happy and it's just for fun, but as soon as I make a few mistakes I'm getting in a downfall.

I don't like it and I certainly don't like it for my double partner. But I just can't control myself. It's not that I get aggressive or something, just frustrated with myself and a bit grumpy. But it makes no sense why because we play at such a low level, it should be just fun.

I want to enjoy the matches en be fun and happy, because that creates better vibes and often better playing!

Anyone who recognizes this or have some tips?