My SO need reassurance

My SO & I have known each other for 9 months now but we been together for 5 months he constantly ask me do I love him & you are going to leave me are you ?or why do you love me? of course I reply to his question I tell him 1st of all you put your kids 1st I find that very attractive I love you for that & he makes me feel so secure in our relationship he doesn’t treat my kids any different from his own biological kids but what else can I do to show him & let him know I’m here for him I’m not going anywhere as long as we respect ,love & honor each other