Although it's heavily based on many of Marvel Comics' best stories and events, the Marvel Cinematic Universe (MCU) isn't an exact one-to-one adaptation of the source material. This is to be expected, especially when the franchise in question is based on decades-old comics. As a result, Marvel changed many of the comics' romances for the big screen.
Source:https://www.cbr.com/mcu-relationships-not-in-comics/