10 Crazy In-Universe Rules MCU Characters Must Follow

In 2008's The Incredible Hulk, it's made clear that Bruce Banner (Edward Norton) can't have sex with Betty Ross (Liv Tyler) for fear of hulking-out and, well, killing her.

This is reiterated in Avengers: Age of Ultron, where Bruce is unable to consummate his relationship with Black Widow due to the fatal potential of him getting excited and becoming the big green guy.

Now, while Banner managed to successfully merge himself and Hulk into Professor Hulk/Smart Hulk by the time of Avengers: Endgame, that seemingly didn't do much to change his celibacy vow. Initially, anyway.

Though Banner clearly exerts far greater control over his Hulk from, at this point in time he's still very much bound to the physicality of the Hulk, and so it's impossible to see how he can have sex with a human woman.

Yet there is a sliver of hope: Banner inexplicably appeared in human form in Shang-Chi, yet is shown as Professor Hulk once again in the She-Hulk trailers, perhaps suggesting that Banner has found a way to switch between the two forms at will.

As it stands, though, Banner's celibacy is most likely still in tact. It doesn't seem probable that Banner would risk a sexual encounter unless he was 100% sure he could stay human without even the faintest possibility of hulking out.

Hopefully She-Hulk will shed light on this deeply pressing matter when it premieres later this summer.