As an older woman who was dating a younger Indian man for 1.5 years (both in the same US city, ages 27 and 38 when relationship started) and it ended because of family, this was my experience:

• The Indian family raises the son to believe that his sole responsibility is to make his parents happy. They come first and you don’t go against them. According to my ex “my life is not my own.”
• The Indian parents often tell them things like they can marry whoever they want, they will not be controlling in a choice, they will not push them into an arranged marriage, etc. It’s a lie they tell the son to keep him happy and feeling like he’s a man in control. So then he takes this literally and dates someone of his choosing who may not be a traditional choice.
• Once he presents them for marriage, the parents totally flip to traditional and say no because of things like age, ethnicity, religion, caste, horoscopes, height, jobs, etc. They totally backtrack on everything they said before.
• Because you usually don’t meet Indian parents until you are ready to get married (not while dating), these relationships usually go on for years before the rejection comes.

So it’s not so much a case of do your research, it’s a case at least in mine of being reassured over and over the age was not an issue every time I brought it up, told this was a liberal family who is not like all the others, but in the end they always end up being like all the others.