My fiance said i wasnt as tight while we were having sex and i am 4 months pregnant. is this normal or is it something i need to work on?

Normal: Your fiancé might work on being a reasonable, sensitive partner with realistic expectations. Pelvic floor exercises ("Kegels") help keep you fit and firm as can be, but vaginas do change with time and use. Sex can and will remain enjoyable for both partners but isn't always the same. http://www.prevention.com/fitness/strength-training/pelvic-floor-exercises-prevent-urinary-incontinence