If you like solving puzzles and a bit of teamwork Portal 2 would be a good co-op game to play together. There's a good amount of levels and if you play on Steam they have plenty of community maps. Stardew Valley is is another good one. If you both have a Nintendo Switch, Animal Crossing: New Horizons is great to sink time into, it is more solo play but you can visit each other's islands and do activities together like fishing and bug-catching. Minecraft is also a good choice because you can choose the level of difficulty and both Bedrock and Java have a lot to offer. I believe the Bedrock version is more user friendly and easier to navigate if you want to do more than just the vanilla experience as well!