With twin brother Joel Madden holding off on marrying the mother of his child, girlfriend Nicole Richie, Benji is playing coy when it comes to wedding bells with girlfriend of two and a half months, Paris Hilton.
"We have a really great friendship, you know, and romance, all of it," Benji, 29, told PEOPLE at Monday's Hornitos Cinco de Mayo party in West Hollywood, when asked if he and Hilton wanted to escalate their relationship beyond dating.
"We're really happy," Madden says. "We're lucky. We're just enjoying it, you know?"
Hilton, who was hand in hand with Madden at the bash, was equally tight-lipped about their romantic future.
"We're very in love," Hilton said, smiling, wearing her trademark sparkler "BM" ring on her ring finger, for Madden's initials.
Asked if they had gone engagement ring shopping, Madden laughed and said, "Come on, man, you know."
Inside the party, brothers Joel and Benji sat with Paris around a circular booth and grooved to pal Samantha Ronson's DJ set while new mom Richie stayed home.
Also at the party: Lindsay Lohan, The Hills' Lauren Conrad and Lauren Bosworth, Dave Annable, and Jane's Addiction's Perry Ferrell.
Joel says he doesn't rule out Hilton and Benji unexpectedly tying the knot.
"Those two are crazy," Joel says. "They do the unexpected, so who knows? Obviously, me and Nicole have been together longer, but we have no plans yet, so who knows."
Paris Is 'Very Supportive'Brothers Madden hit the road this summer for an international tour with their band Good Charlotte to promote their fourth album, Good Morning Revival. Hilton says she'll be joining the band on tour.
"She's a very supportive woman," says Benji. "Whenever we go out there ... she's part of the team. She's great. It definitely makes touring easier. She's like the best teammate you could have, she's very supportive. So, I'm blessed."
Hilton and Madden's whirlwind romance continued this past weekend in Orlando, Fla., where the couple hit thrill rides at Walt Disney World.
They have already toured Africa and Europe together this year.
"We went on every single ride, like three times each," Hilton said.
Adds Madden, "I know we probably sound cheesy, but we're such happy guys right now. We have so much to be happy about. Our families, all the babies, (bandmate) Billy just got married. All of us are in love. We're a happy band."