Most people quit
European Portuguese has a reputation for being brutal, and the reputation is only half earned. The grammar is not the problem. It looks much like Spanish or French, and anyone who has studied either will recognise most of the machinery. The problem is the sound of it.
Most people who start do not finish, and the ones who drop out are rarely the least committed. They are usually doing something specific and fixable, and there are five candidates worth checking yourself against.
1. Learning the wrong Portuguese first
Brazil has the overwhelming majority of Portuguese speakers, so it has the overwhelming majority of the material. Apps, YouTube channels, textbooks. The plan most people form is reasonable on its face: learn the basics from whatever is available, adjust the accent later.
It does not work, because the accent is not a layer on top. The two varieties run on different rhythms. Brazilian Portuguese is syllable-timed and open; European Portuguese compresses everything that is not stressed. Learn to hear the first and the second arrives as noise, which is precisely the moment people conclude they have no ear for languages.
Stay with mainland material from day one. The silent e, the "sh" at the end of syllables, amo-te rather than me amo. Half-learning both leaves you stranded between them.
2. Mistaking a streak for progress
Gamified apps got a lot of people started who would never have started otherwise, and they have produced a particular kind of stuck: three hundred consecutive days, and still nothing at the bus stop.
Tapping the right answer from four options is recognition. Recognition is easy and it feels like knowledge, which is the trap. What builds recall is producing the thing without the prompt in front of you, and that is uncomfortable in a way an app is specifically designed not to be. If it never feels like effort, check what it is actually training.
3. Waiting until the grammar is finished
This one catches the academically minded hardest. Months on conjugation tables for the futuro do conjuntivo before ever ordering a meal, on the reasonable-sounding theory that you should know a thing before you attempt it.