A single father is not inherently a red flag. Being a single parent requires strength, responsibility, and commitment, which are admirable qualities. However, it's important to be aware of the specific circumstances and dynamics of his situation.  Look for how he manages his responsibilities, the relationship he has with his children, and how he speaks about co-parenting with his ex-partner.  A single father can be a great partner, but like any relationship, it's crucial to understand the individual context and whether it aligns with what you're looking for in a relationship.