Chance at Love by Tess St. John

Lady Lorna Keys has taken over her late husband’s responsibilities until her son is of an age to run the earldom. With the Swing Riots striking close and pressure from her husband’s uncle, Lorna becomes concerned about her son’s safety.
Lorna’s brother rescued Hamilton, Viscount Voss, from his abusive father when he was sixteen, and her family hired him as a servant. Five years ago, he revealed his true identity and reclaimed his title. The ton disapproves of the way he lived as a servant; therefore, he gladly avoids the peerage and will never trap a woman into marriage.
When Hamilton arrives worried about Lorna, she realizes a marriage of friendship to him will solve all her problems.
Taken aback when Lorna proposes, Hamilton understands she and her son need protecting, but he cannot abide the platonic union she offers and makes a proposal of his own—one that might give them a chance at love.

CHANCE AT LOVE is Book 5 in the Chances Are Series. Each book stands alone, but might be more enjoyable read in sequence.