You know, I can't say which route is better for you but how about I tell you a different perspective.
When my dad passed, my mom decided she didn't want to remarry. She wanted to spend her life taking care of us kids so we'd never question why our life wasn't like others or how come we didn't have this and that. It's been almost 10 yrs. since that decision and sometimes I wonder what's going on in my mom's head. I always wonder if she'd be happier with a companion? There's only so much children can provide for their windowed parent and it gets to me sometimes. I've even hinted to my mom that we would be okay if she wanted to find someone to be by her side. She still shakes her head and insist she wants to raise us well on her own. Part of it might be like what you have mentioned about "fearing partner's love for one's children". I know I've had conversations with her about hearing stories of how step-fathers molested their step-daughters. I bet that gets her thinking and she just scratches the idea of remarrying out even more. If anything, I'd want my mom to be happy. I know she often gets lonely and I get sad about it.

Although DonJuan comes off a little harsh and direct there, he does make a few good points. Since your children are still young, it might be wise that you focus on making sure they are on their two own feet first. I think if my mom had taken the other route and married when my siblings and I were still pretty young, my life wouldn't be where it is now. Now that we've managed to find our paths, we've given my mom two thumbs up and assured her we'd be okay if she wanted to ever find a partner or remarry.