Just realized I never clarified this with anyone.

Probably one of my most important Soul Eater headcanons.

I actually don't think Spirit ever had sex with another woman after he married his ex-wife. I think that like Maka, his ex-wife was overreactive and slightly feministic, and she saw cuddling and kissing with other women as offensive to her relationship as most people see sex with other women. Despite what we've seen in the anime/manga, I really can't see Spirit as the type to just want to get into someone's pants. I think he spent time with other women because of personal issues that made him crave attention. I also think that he married his ex-wife in the first place most likely because they were going steady as teens and he got her pregnant, and then they tried to cope with each other in order to raise Maka and not subject her to a young life with a single parent. I don't think Spirit was ready to commit to a relationship of that level and judging by how Maka described her mother's personality he probably felt trapped by her. Basically I think that Spirit tries his best to be faithful to everyone despite the fact that he obviously has issues with feeling alone and needing constant attention. I just can't see him as a douchebag who would knowingly do something to wreck his family, and I feel like it's unfair that Maka and her mother act like he was deliberately trying to hurt them and don't try to understand that by distancing themselves from him they're just making his depression and resultant need for attention worse.