So, as a significant other, I say go for it and don't look back!
I'm a cis woman and my boyfriend is FtM, but he hasn't transitioned in any way (however he already masculine in features and the way he dresses). As for my sexuality I'm not sure what I identify with (that's for a different discussion though). But I did identify as a lesbian when I first met hit, and only within the past few months has he come out as trans and is looking to start his transition.
Trust me, our relationship is no walk in the park, but what relationship ever is? We have our ups and downs like any other couple, and sometimes it is related to him being trans and the struggles he faces and my role during his transition.
I see no problem with going stealth, but, it's my belief that if you do find someone that you are truly in love with and has committed themselves to a relationship with you for YOU, then eventually whether you tell them you're trans or not, they'll still love you. I never thought I'd be with a trans guy, and be so in love, but it happens, and it happened to me. And I wouldn't change that for the world. You have to put yourself out there though.
I know putting yourself out there is easier said than done, but it's a step. Even if you go on one silly date with someone, at least you'll know what it feels like and you can see how to act in the future. (This goes for anyone getting into the dating scene, not just someone who's trans). Do not ever underestimate yourself, or the fact that there are billions of people in this world, and one was meant for you.
No matter what, just please remember, we accept the love we think we deserve. Don't let anyone take advantage of your kindness, or your vulnerability of being back in the dating game. Don't sell yourself short, because whatever you think you deserve, you probably deserve even better.
Sometimes when we step outside of our boundaries, we surprise ourselves and others as well. No matter how old, no matter what stage in life you are in, anything is possible.
good luck!
xoxo