I'm going to chop up and rearrange bits of your post here in my response to put together the things I want to respond to. Please feel free to correct/clarify if this changes the context (and implications) of what you have said.
I am accepting of her, should she choose to have different partners, as long as she is open and honest about everything that happens. Only recently has she actually taken me up on this... She wants to have two partners, something I think is referred to as a V-type relationship? With her in the middle. But wanting a long lasting relationship with two men... I don't know if I can be happy there.
First off, yes, that would be Vee relationship - unless the two men are also involved, in which case it would be a triangle/delta. Openness and honesty are two things which many polyamorists agree are necessary to the whole endeavor (and even there you will find some disagreement - we all "do" poly differently) - so, from my standpoint, that is not a bad requirement.
So, you say that you are accepting of her having other partners BUT are unsure about a long-term Vee with two men? Is this because you are uncomfortable with her having another
male partner or because you would be more comfortable with her having more short-term, non-committed relationships (or both)?
She is not alright with me having other partners. I have had a bad history of infidelity and she and I are trying to make our relationship work in spite of this. What this means though, is that she is afraid of me drifting away from her, of losing me to another woman.
Reading here you may come across the term OPP - many use it negatively. It usually means "One Penis Policy" but can mean "One Pussy Policy." I don't think it necessarily is a bad thing if both partners are in agreement. BUT I think that you will see a lot of advice here that discusses that imbalance - when the "rules" are different for two partners then resentment can ensue - and it often NOT a good long term solution. She is afraid of losing you to another woman, but expects you to not be afraid of losing her to another man (or woman)? Hmmm.
I think the history of infidelity means that you have to be very, very careful - but I think that I would separate that issue from the fear of losing you, it sounds kind of like an excuse as to why she can do what she wants and you can't. I think the infidelity/trust issue has to be addressed by itself - it sounds as though there are unresolved issues here...
And she would be alright with me having feelings for the other man... but I don't know that that will happen...I am... well barely Bi. I have not actually found myself sexually attracted to a man, but I would not be against the idea.
Of
COURSE you don't know that it will happen. This is all theoretical - you haven't even MET the hypothetical other guy yet! There is no reason to expect that you would fall for a guy just because your partner does - even if you were bisexual to the
nth degree. Bisexual people aren't attracted to every person of either gender that they meet - just like purely straight/gay people aren't attracted to every member of the opposite/same sex they meet. On the other hand he could turn out to be the ONE guy that floats your boat...you never know, you WON'T know until you meet him.
My partner and I have been together for many years... I want her to be happy. And she is willing to forgo the whole thing if it bothers me... I worry that I am not right for her.
Only she can say whether you are "right" for her - at this time, in this relationship. She is with you by choice - and has been for many years. I would take that for what it is worth and strive to be the best person and partner you can - both for her sake and for yours - as should she.
******
For the record, for years and years my husband was fine with me pursuing relationships with other women, but thought that he couldn't "handle" me having a relationship with another man. And I was ok with this - being bi, I thought that I "had" my guy and was "looking for" my gal. Then Dude happened. I wasn't prepared for it - I handled it badly (you can read about it in the /Jackassery/ portion of my blog here).
After a period of turmoil, though, it turns out that he
could handle it - we have been a functional co-habitating Vee for 18 months now, and I am amazed by how ALL of our relationships have evolved and strengthened in this short period of time. Was it because, after 19 years together, he
knew I wouldn't be "leaving" him for anyone? Was it because Dude is his best friend and they love each other as much as two straight guys can? Both? I don't know - I don't think you can make any generalizations. In my opinion pretty much everything depends on the individual people involved - practice trumps theory any day of the week.
JaneQ