I don't know anywhere with rainforest suitable closer than Costa Rica, we've been to Brazil, Costa Rica and Australian rainforest so same or further and Costa Rica one was the best.
My DH and DS come on holiday easily now but when met DH he always said he wanted to go on holiday but any destination he hadn't been to before was ruled out and he would never reach a decision. Same with houses, a year of every weekend looking round houses. In the end I would just book something and tell him he was going, same with house. With the TUI ones in Europe we would have a three day I hate change moaning period then fine then with animal themed ones if we saw animals on day 1 he was fine straightaway so have stuck with animal themed ever since. The first three day thing I leave him in his room and take kids out so go to resorts with lots on sites. He works better in places with 2 rooms so we can shut him in one. 😂
This only works though if he's not going to moan all holiday. In that case maybe divorce would leave him home and go without him. Would he be OK with kids though? Could grandparents help - my DH is great with practical things but couldn't deal with any kind of emotion / tantrum and always would worry one or other of them would have killed the other if left alone together. I remember explaining this to work once and they thought I was joking and insisted I stayed overnight then asked me how it went. Thankfully he at least had the sense to call my parents down from 4 hours away.
Costa Rica is 11 hour flight and 5 hours behind so 1 week is pushing it but time difference didn't affect me as they start tours etc at 6am so felt like a tour starting at 1pm. You could see a lot in a week, at hotel RUI Guanacaste, there was kayaking, windsurfing, SUP in ocean included, AI, raccoons, coati, gecko and pelican we saw at hotel, raccoons almost every night - by steakhouse. Walk 50 metres and there's monkeys, its in rainforest. Next door there's Diamante with a zipline and other rainforest animals, zipline goes 60mph from very high up to ocean. Tour company on beach Gecko Tours can horseride on beach with and tours to see sloth in rainforest, Buena Vista, active volcanoes, horse riding and waterslide through jungle and hot springs and lower zipline where you zip past monkeys and toucans. Also trips to botanical gardens, Arenal volcano, Monteverde hanging bridges, quite a few others, we did 5 over two weeks. I would tell him you've booked for yourself. 😂 Closer on own maybe Azores but not been whale watching and swim with dolphins, do check timetables on these things like, some things aren't all year. If you go on own may kickstart him into coming with you next time though you might no longer want that