The Matriarch by Jen Talty

After the death of her husband, Catherine Sarich dedicated her life to her four boys. Now that each of them has found love, gotten married, and started families of their own, Catherine finds herself wanting more out of her life than babysitting her grandchildren. While her boys and their wives keep pushing one particular man in her direction, she’s never really embraced being single, or dating, so she signs up for a dating app.
Mistake number one.
Even though she finds retired Green Beret Wesley Maron incredibly attractive and insanely sweet, she finds herself shying away from a man who reminds her too much of her late husband.
But when a suitor turns deadly, she turns to the one man who not only has her best interests at heart but loves her unconditionally, even if he too is struggling to open his soul to love again.
Wesley Maron spent too many years pining over his ex-wife. When he finally finds the woman who has the ability to flip his world upside down, he finds himself having to accept the fact she’s not into him and wants to date other people. Protecting his heart, he gives Catherine all the space she needs in hopes someday she will realize her true love is right down the street. But when one of her dates turns out to be everything other than a gentleman, he decides to take matters into his own hands, even if it means laying his life down for the woman he loves.