Yes, according to research, it is completely normal to still love an ex even after 4 years. Many individuals find it challenging to move on from a significant love they once shared.
The reference states: "It is completely normal to love an ex still after the relationship is over. For many people, it can be hard to move on from real love. When we fall in love, everything seems so perfect, and we feel it will last forever. Unfortunately, that's not always true, and sometimes relationships do end." (13-Oct-2024)
When relationships end, the feelings don't always disappear instantly. It can take time, and for some, the love might linger for years.