Your messages (like always!) are quite tricky to translate. Though they may seem quite simple in English, it is not the case in Gujarati. In English there is a lot of vagueness I think - what exactly is meant by the expression "Sorry I am not part of your future"? Does this mean you feel sad? Does it mean "forgive me that I am not.."? Does it express "it is your fault that I am not part of your future"?
My translation for the moment would be:
ભવિષ્ય માં ખૂશ રહેજે, હું એનો ભાગ લેવાનો નથી એટલે મને ક્ષમા કરજે. મારુ દિલ અજેય નથી.
(bhavishya maa khuuSh raheje, huN eno bhaag nathii levano etle mane kShamaa karje. maaru dil ajey nathii.)
Literally: Stay happy in the future, forgive me that I am not a part of it. My heart is not invincible.