Surprise pendant engraving. Need help fast!?

My boyfriend and I have been talking about getting a puzzle piece pendant necklace and a slot into one another, but have never got around to doing so. He's really eager to get it ask he often brings it up but I haven't had to time to search for one at reasonable price. And I want to surprise him for Valentines Day with it.

This morning I took it upon myself to look for one and found one that we can get it with an engraving but I'm having trouble what to write on it. I'm definitely going to put our anniversary date on it but I don't know what else to put. On his one I was thinking to just have I love you but I don't just want the date on mine because its a bit plane and boring.

Do you have any suggestions as to what I could put on them even a sentence that is completed when we place them together?

Thank you for any suggestions, I really appreciate it lovelies :)

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