Ben: I'm so batty about Jen.
The 32-year-old - whose high-profile affair with diva J-Lo ended in February - treated his new Jen, also 32, to two weekend matches.
The couple, who met on the set of Daredevil, braved the cold to watch Affleck's beloved Boston Red Sox's opening World Series games.
They shared a hotdog and cuddling as fellow fans around them cheered at Boston's Fenway Park on Saturday and Sunday.
Affleck, the star of such films as Pearl Harbor, Good Will Hunting and The Sum Of All Fears, was approached to throw out the first ball before Saturday's game but he declined.
But he started the week a very happy man after his team won the first two games.
Alias star Garner divorced her husband of four years, actor Scott Foley, earlier this year.
She will next be seen in the action adventure movie Elektra.
It is an off-spin of Daredevil, in which her high-kicking heroine Elektra Natchois is released from hospital to embark on an assassination mission.
FAN: Affleck; LOVE: Garner