Spouse visa

Hello all,

I came to U.K in 2011 and was on student visa till October 2016. However, before my visa expired I made an application to home office regarding my willingness to marry my partner and enter in Civil partnership. While that application was on going me and my partner got married in U.K ( legally and it was approved by Home Office) and applied for spouse visa in May 2016 under 10 y route. Which was refused last week. On the ground on eligibility and suitability. Reason stated by home officer were:- they don’t see any reason why can’t me and my partner (White by race) can’t move to India and live there. Even though gay marriage is not legal in India. Also they said I was in India till age of 19, so I can move to Mumbai or somewhere else and I can easily integrate to the society. But they did not talk about my partner who is born here, his mother is only his surviving family who is sick ( to which home office said NHS CAN HELP HER). I find it very unfair and feel very angry that why can do this and get away with it.
I was rather baffled after this letter, luckily they gave me chance to appeal which I will go ahead with. Also they gave me letter saying person liable to be detained and have asked to sign.
Now my question is-:
If I never overstayed and abide by rules and paid all my taxes, can Home Office still correct in sending that letter?
Is it safe to sign and what can I expect there?
If anyone have any advise or have gone though this please share your experience.

Many thanks