Seven years ago, divorced and diagnosed with bipolar disorder, Pete Wentz never thought he’d be as happy as he is now. “I have a cool partner, I have a cool job, and I feel very lucky,” says the Fall Out Boy bassist, 38. Currently on a world tour promoting the pop-punk band’s seventh album, Mania, Wentz has plenty to celebrate. He will welcome a daughter this year with his longtime partner Meagan Camper, with whom he shares son Saint Laszlo, 3. He is also dad to 9-year-old son Bronx Mowgli with his ex-wife Ashlee Simpson, with whom he shares custody. “We have a lot of testosterone in our house,” says Wentz, whose two male dogs—Bearenstain, a Hungarian Vizsla, and Bowie, a husky—complete the family. “I see my friends who have…