Dear Shalini,
Hope you are doing well! I'm writing 
this
 letter to tell you about our sudden plans for relocation, due to which we have decided to vacate our current accommodation. I can't explain to you, how much we enjoyed your company during all these months of our stay.
Sadly, Linking Words
31st
 of Correct article usage
the 31st
this
 month will be our Linking Words
last
 day here. From here, I will be flying back to Delhi at my parent's place and my husband will shift to his mom's house in Mumbai.
You will be excited to know that I've got a job offer at India's biggest immigration company with a very attractive salary package and other benefits. There is just one thing Linking Words
which
 is making me upset is that the job location will be Delhi and not Mumbai, due to which I will have to relocate. But believe me, the proposal is worth considering.
I can't express to you how happy I am about Correct pronoun usage
that
this
 chance but at the same Linking Words
time
 I'm really gonna miss you and all the fun and parties we did together. 
Best Wishes,
Sweta SinghAdd a comma
,time