Is It Okay to Mix Past Tense With Present Tense in Story Writing?

I’m rather late, so let me see if I can provide an answer that’s not been given yet.

The simple answer is that you can but shouldn’t if you’re a novice. To give an example:

Fine: Bob Pancakes shows us that he really loves Eliza Pancakes by making her breakfast.

Fine: Eliza Pancakes absolutely hated Bob’s cooking and vowed to trash it each morning.

Not Fine: Bob told Mary that he loves Eliza’s outfit.

To write this, it would go something akin to, “Bob created a fine dish in the morning, his eyes had focused on the pan with a precision that had never been done before. He had cooked up an excellent quality dish that he was sure Eliza would love! Now, he needed to go and wake her from her sleep.”

You’ll note the entire thing is in one tense (I hope, I rushed it and didn't proofread xd) and therefore reads better than mixing them.

“Bob cooks Eliza breakfast each morning. It showed his love for her. He created pancakes with some salt and pepper. He finished it and walks to their shared bedroom, where he opened the door and hands her the food.”

The funny thing about writing is that you really cannot go wrong. Write what you love, how you love. People will argue about grammar, punctuation, tense, person, setting, and whatever else they want to. Write how you want. The human mind is very good at correcting any issues it sees. Mixing tense isn’t bad, swapping from first to third person isn’t bad. Do it how you feel is the best and don’t really worry about others.

Unless of course you’re writing a book and publishing it. I then suggest you take your time and such. Your editor (if you have one) will thank you. For Sims fiction, you’re fine.

If you want an unethical life tip, just say English isn’t your native language and all transgressions will be forgiven.

Basically, no. Your example is incorrect.

You need to use phrases like "Paul replies" or switch to full past tense.