There's 2 main issues at work here:
1) There is no nuance between "Friend" and "Romantic Partner".
It's incredibly hard to maintain a platonic friendship without any romantic advances because there's no tangible line of specifying you're interested in someone or not. By default just being nice to someone ends up with you on the romance path, unless you're specifically aware of which dialogue options trigger things (Even then it surmounts to you having to turn them down at some point)
2) Relationships are shallow.
This applies to both friendships and romance, but is more egregious for romance.
The act of developing a relationship is simply "Do things X character likes" and eventually you'll just be BFF's/lovers. Heck, you don't even need to talk to them ever or even have them in the party (Thanks to BG3's psychic companions, they can fall madly in lust with you with absolutely 0 interaction).
Which is really silly and leads to the situations in BG3 that irked a lot of people, which is companions coming onto their character from out of the blue. Since this act of pursual was triggered simply by doing enough general things they liked - Again, irregardless of if they were in the party or were being interacted with.
Now, as for solutions to such issues:
1) Provide more dialogue options and make it more evident when options are flirtatious or simply being friendly.
This doesn't necessarily have to be direct professions of love right out of the gate. But there should be obvious signs that differentiate "Getting to know a friend" and "Trying to woo a romantic partner". Really, there'd be different levels of "Forwardness" to which characters will react differently based on their personality (As well as overall relationship level)
2) Improve on the very basic and very outdated relationship model.
We need to do away with the simple "Like-o-meter" whereby characters just gain favour from doing basic things like "Do something they like" or "Give them a gift" and then instantly fall in love with you once it reaches 100%.
There needs to be systems that are more nuanced in how characters react. With more things that can influence how a character views you. Such as how often you talk to them, how much you converse with them, whether you bring them along in your party, the priority you put on interacting with them (I.e. They'll like it if they're the first person you talk to when you get to camp and start to resent you if they're the last person in your rounds of talking to everyone) etc.
Also, it should be made so that positive feelings don't necessarily equate to romance. Allowing you to become BFF's with someone without having to dance around constant romance requests. Of course, this would be very complex to do well without simply making it based on a "I want to romance you" dialogue option... Though even that basic implementation would be far better than current systems (That's how awful they are)
It should feel more organic and more like you're going out of your way to get closer to a character. Rather than just ticking checkboxes to fill a relationship bar (Of course, it will always boil down to essentially this. The key is to mask it with complexity so it's less obvious)
