基本上無問題. 但要注意嘅係通常在季節前都唔會加 "the"嘅, 除非個季節係用作形容詞.
Eg.:
Summer generally refers to the warmest and humid season between Spring and Autumn.
The Autumn leaves are of a yellowish colour.
所以你呢句應寫成:
My Sweetheart will be back in Summer.
或
My Sweetheart will be back in the Summer holidays.
更親暱的可寫成:
My love will be back in Summer.
My soulmate will be back during the summer holidays.
My sweetie will be back in town this/next summer.
My man/girl will come back to my arms this summer.
My better half will come back for me this summer.
My love/babe will fly back this summer.
My sweet darling will be with me again in the summer holidays.
My dearest honey(hun) will return this summer.
My lovely cutie/cutey will return to Hong Kong this summer.
My honey bunny will be in town for me this summer.
My adorable cutie pie will be coming back this summer.
Note: better half (spouse) hun(slang) = honey
will be coming back <---- future continuous tense (higher possibility)