Complex sentence: Ruth and Mark argue and Ruth grows closer to Mark's cousin, Conor Flaherty (Seán Gleeson), who is staying with them then Jessie's mother, Nicole, visits and tells them she is taking steps to get Jessie back.
Split into simpler sentences: Ruth and Mark argue and Ruth grows closer to Mark's cousin, Conor Flaherty (Seán Gleeson), who is staying with them. Then Jessie's mother Nicole returnns, declaring that she is taking steps to get Jessie back.