Yes. I've seen some comments defending Sol's action towards Ian (as a Brian stand in honestly because of shared souls/reincarnation. I try to think about Inuyasha with the Kagome/Kikyo situation. They are different people though they may have similarities. They may share a soul but they are their own identities because of the lives they have lived. It would be best if Ian never regains the memories because they are not his. They're Brians. If Sol truly loves Brian in any form he will love Ian as Ian.
Exactly I think people are defined by the lives the lead, the people they meet, experiences they have that's what shapes your personality so even if that have the same soul they are two completely different people who've lead completely different lives ykwim so it's not fair to Ian to be loved for being someone he isn't if that makes sense (I will add that I haven't read this manhwa in a while so I'm not sure where the story is at now but this was my opinion when I was a more diligent reader)
The more focus ww get on brian and sol the more it's gonna Hurt when it get backs to Ian imo. It's just the more you see why sol fell in love w Brian when we go back to the present it would feel like he still loves Brian and is looking for brian in Ian and thats just not fair to Ian man