That's a good question

Brand loyalty, Purchase decision

Not sure what do you mean. Maybe this can help you https://www.researchgate.net/publication/256051252_Antecedents_and_Consequences_of_Brand_Love

I think you can consider post purchase behavior (satisfaction) and future purchase intent

Brand love and...WOM outcomes, consumer‐brand relationships, personality, image , brand loyalty...

Carroll, B. A., & Ahuvia, A. C. (2006). Some antecedents and outcomes of brand love. Marketing letters, 17(2), 79-89.

Leventhal, R. C., Wallace, E., Buil, I., & de Chernatony, L. (2014). Consumer engagement with self-expressive brands: brand love and WOM outcomes. Journal of Product & Brand Management.

Albert, N., & Merunka, D. (2013). The role of brand love in consumer‐brand relationships. Journal of consumer marketing.

Ismail, A. R., & Spinelli, G. (2012). Effects of brand love, personality and image on word of mouth. Journal of Fashion Marketing and Management: An International Journal.

Drennan, J., Bianchi, C., Cacho-Elizondo, S., Louriero, S., Guibert, N., & Proud, W. (2015). Examining the role of wine brand love on brand loyalty: A multi-country comparison. International Journal of Hospitality Management, 49, 47-55.

Dear Ahmed,

There won't be one right answer to your questions since you could test a lot of different variables in connection with brand love. Not only could you test different (brand-related) variables but also the role of the variable can differ, e.g. is it an output variable, or a mediator, or moderator etc...

I would recommend that you follow a thorough literature review on brand love and see what the field has investigated so far.

I agree with Samuel Kristal sir. There could be many variables that have an association with brand love. It depends on the objectives of your study which one to be chosen. Better to have an in-depth review of available literature.