She could arrange a day out together, like a picnic in a secluded place, and then when the mood is right, initiate a passionate moment. Another idea is to write him a love letter full of hints about the surprise sexual encounter and leave it where he will find it easily.
Preparing a special setting such as a room filled with roses and soft lighting can be a great way. Also, cooking his favorite meal beforehand can add to the surprise.
She could buy tickets to a sports event of his favorite team. He'll be really excited when he finds out. For example, if he loves football and she gets tickets to a big game, it'll be a great surprise.
You can plan a surprise weekend getaway. Book a nice hotel in a place she has always wanted to visit, like a cozy cabin in the mountains or a beachfront resort. Then, pack her bags secretly and blindfold her on the way to the destination.
She can cook his favorite meal and set up a romantic dinner at home with candles and soft music.
Buy her a piece of jewelry that she has been eyeing for a long time. It doesn't have to be super expensive but something that has a special meaning. Present it to her in a cute way, like hiding it in a box of her favorite chocolates.
You can buy her a piece of jewelry she has been eyeing for a long time. It will surely make her happy.
Plan a weekend getaway. Book a hotel in a nearby town he has always wanted to visit and keep it a secret until the day of departure.
Plan a weekend getaway without her knowing. Book a nice hotel in a place she loves or has always wanted to visit. Pack her bags secretly and on the day of departure, tell her to get ready for a surprise trip.
A naughty wife could plan a weekend getaway to a place he has always wanted to visit but never had the chance. She can keep it a secret until the last moment and then see his face light up with excitement.
A wife can surprise her husband by redecorating his study or home office in a way he has always wanted. For instance, if he loves a certain sports team, she can put up posters and memorabilia of that team. This shows that she pays attention to his interests and is willing to make an effort to create a space he'll love.
One way is to misdirect the reader. For example, introduce a character who seems to be the hero but turns out to be the villain in the end. Another method is withholding key information until the very end. This could be a secret about a character's past or a hidden motive for their actions. Also, using unexpected plot twists like a sudden revelation that changes the whole meaning of the story can create a surprise ending.