Ukrainian. I started shortly after my wife, who is Ukrainian, and I got married. It didn't last long before I stopped/gave up since she wasn't too interested in speaking it other than to her parents. Her family came to America when she was very young (and the youngest of 4), so she's much more comfortable with English.
Fast-forward to last February where I picked it up again after Russia invaded. Got through the Duolingo course, but feel like I hit a plateau of sorts and need to get motivated again. I have a physical book, pimsleur, lingq, and anki cards--just need to practice and build up more vocabulary.
I tried out Ukrainian aswell after the war broke out. Yeah, Duolingo sucks for Ukrainian, I hate to say it. The difficulty with the language is all of its grammar, declensions, conjugations, what not. Duolingo barely teaches that and only focuses on words, which in all honestly gets you nowhere. I'm hoping to pick up the language again, it's beautiful.