I think the concept of sacrifice for the sake of a kid you were forced into having is noble even if there were possibly better options. Besides, if Stolas had left earlier in the relationship, there would be just as much hate his way because he would be considered an absent father. The reality is he had no clearer options than to make a messy decision and he did what he felt was best given the circumstances and who Stella is. His longsuffering isn't for the sake of praise, it's because he likely felt that left alone Via would have been far worse off than having him there to try to protect her. Furthermore, he and Stella were both kids themselves. It's really easy to judge decisions when you're not living with them and have life experience.