i live my gf but i think i may be gay/bi

Sorry for the long post/read
I (28m) my gf (25f) and other guy (23m)
Ok so as many of us know we all had the “lockdown “ and for many people they did fine.
For other not so much me and my gf did ok but not well she got pretty lazy and moody dealing with depression.
She put on a bit of weight and I got pretty lazy and also put on a lil weight her more then me we have both been working on ourselves to get better I’ve been exercising just about everyday weights and bike rides , sit-ups stuff like that.
I have also changed up my diet and cut out a lot of junk that part makes me feel so good about myself I’ve even been working on my posture I stand straighter now and have less stress in my shoulders.
So for (25f) gf she was doing pretty good before the lockdown she was slowly losing the weight she still had on and even doing pretty solid mentally.
We was doing pretty good honestly despite general life issues we were happy it was 4 years together before the pandemic at 6 years now and she’s not the same anymore.
She stopped really going to the gym and stopped being more productive and has started therapy again because mentally she has gone down hill I know it’s the depression and I’m doing everything I can to be supportive and loving.
She has a doctor’s appointment next month to talk about all the meds she is currently on I hope that bring some good news and changes.
I just want her to get better with or without me I care that much I feel like the love is thinning we care very much for each other I just don’t know how much longer this will last for us.
Ok so for the (23m) lets call him “bob” so I met bob through my brother they work together he’s a mechanic Bob’s been hanging out with me and my brother at our weekly fires n beer.
Bob is more my brother friend then mine but we’ve had our moments we talked we got a good bit in common
We both grew up in the country we both got our grandpas truck as our first both Chevy S10s both manuals his was older then mine.
We are both pretty quiet unless directly spoken too we both enjoy the quiet and outdoors so does my brother though he never shuts up I love him though best fishing buddy one could ask for.
Things were just fine just chillen and bullshitting all the time at the weekly fire’s.
Then just kind of out of the blue I just looked at bob and thought wow I like this guy he’s simple quiet and handsome/cute witch I thought alright cool whatever then the thoughts got sexual I at one point found myself wide awake one night unable to sleep just thinking all that stuff and it “REALLY” turned me on.
Now when ever I really think about him I get butterflies man last I checked I’m not really gay but now I don’t know I’m pretty sure he’s not gay.
Bob got out of a long-term relationship with his last gf about half a year ago.
So ya I could really use some advice or just some wisdom or anything at this point I myself have never really thought like this towards another man before I’m unsure of what to do.

TLDR I love my gf but am having gay feeling for another man