The Netherlands international has spent the last two seasons on loan at the Liberty Stadium from Villarreal, making 93 appearances in all competitions.
He helped Swansea claim the first major trophy in their history when scoring in the 2013 League Cup final, and was also a part of the club's European adventure last season, which saw them reach the last 32 of the UEFA Europa League.
However, a third move back to the Premier League side appears unlikely after Monk admitted he was preparing for the new season without the 26-year-old.
"We talked to him [De Guzman] earlier in the summer, he wanted to keep his options open and I guess his options still are," Monk is quoted as saying by Sky Sports.
"I do not anticipate him coming back at this moment in time.
"With the high turnover of players we have had, and trying to get as much information across to them as possible, we have not got time to wait around.
"I am not closing the door on it, if it happens it happens, but he and his agent were the ones who decided to keep his options open and we can't wait about."
Get the best features, fun and footballing frolics straight to your inbox every week.
Thank you for signing up to Four Four Two. You will receive a verification email shortly.
There was a problem. Please refresh the page and try again.