But above all, is it something bad to be in a relationship?. Really is it sinful to love someone?

It is not wrong to be in a relationship. In fact, I feel (being from the West) having relationships helps a person figure out who they are and what they want in life. Love is never sinful. Love is beautiful. Discrimination is more sinful, in my opinion. I would actually love to hear more on why your parents/culture feels love isn’t a good thing?

I have experience in this, being a Western woman who was left by an Indian male for an arranged marriage (and thus my following statement will be biased). My advice would be that if you aren’t willing to challenge your parent’s beliefs – and the greater culture – to stand up for what you need in life, then you must accept your fate and not involve any other males who you may fall for in a romantic sense. This will take strength and a bit of defiance to cultural practices that have been set for millennia, but unless you are willing to stand up for it, it is not worth dragging the heart of an innocent person into the matter. It is not worth causing someone else pain for a matter that will never work to their favour.